- The ncurses library routines give the user a terminal-independent
+ The ncurses library routines give the user a terminal-independent
method of updating character screens with reasonable optimization.
- This implementation is "new curses" (ncurses) and is the approved
+ This implementation is "new curses" (ncurses) and is the approved
replacement for 4.4BSD classic curses, which has been discontinued.
- This describes ncurses version 6.1 (patch 20181208).
-
- The ncurses library emulates the curses library of System V Release 4
- UNIX, and XPG4 (X/Open Portability Guide) curses (also known as XSI
- curses). XSI stands for X/Open System Interfaces Extension. The
- ncurses library is freely redistributable in source form. Differences
- from the SVr4 curses are summarized under the EXTENSIONS and PORTABIL-
- ITY sections below and described in detail in the respective EXTEN-
- SIONS, PORTABILITY and BUGS sections of individual man pages.
-
- The ncurses library also provides many useful extensions, i.e., fea-
- tures which cannot be implemented by a simple add-on library but which
- require access to the internals of the library.
-
- A program using these routines must be linked with the -lncurses
- option, or (if it has been generated) with the debugging library
- -lncurses_g. (Your system integrator may also have installed these
- libraries under the names -lcurses and -lcurses_g.) The ncurses_g
- library generates trace logs (in a file called 'trace' in the current
- directory) that describe curses actions. See also the section on
- ALTERNATECONFIGURATIONS.
-
- The ncurses package supports: overall screen, window and pad manipula-
- tion; output to windows and pads; reading terminal input; control over
- terminal and curses input and output options; environment query rou-
- tines; color manipulation; use of soft label keys; terminfo capabili-
- ties; and access to low-level terminal-manipulation routines.
+ This describes ncurses version 6.4 (patch 20240302).
+
+ The ncurses library emulates the curses library of System V Release 4
+ Unix ("SVr4"), and XPG4 (X/Open Portability Guide) curses (also known
+ as XSI curses). XSI stands for X/Open System Interfaces Extension.
+ The ncurses library is freely redistributable in source form.
+
+ ncurses man pages employ several sections to clarify matters of usage
+ and interoperability with other curses implementations.
+
+ o "NOTES" describes matters and caveats of which any user of the
+ ncurses API should be aware, such as limitations on the size of an
+ underlying integral type or the availability of a preprocessor
+ macro exclusive of a function definition (which prevents its
+ address from being taken). This section also describes
+ implementation details that will be significant to the programmer
+ but which are not standardized.
+
+ o "EXTENSIONS" presents ncurses innovations beyond the X/Open Curses
+ standard and/or the SVr4 curses implementation. They are termed
+ extensions to indicate that they cannot be implemented solely by
+ using the library API, but require access to the library's internal
+ state.
+
+ o "PORTABILITY" discusses matters (beyond the exercise of extensions)
+ that should be considered when writing to a curses standard, or to
+ multiple implementations.
+
+ o "HISTORY" examines points of detail in ncurses and other curses
+ implementations over the decades of their development, particularly
+ where precedent or inertia have frustrated better design (and, in a
+ few cases, where such inertia has been overcome).
+
+ A program using these routines must be linked with the -lncurses
+ option, or (if it has been generated) with the debugging library
+ -lncurses_g. (Your system integrator may also have installed these
+ libraries under the names -lcurses and -lcurses_g.) The ncurses_g
+ library generates trace logs (in a file called "trace" in the current
+ directory) that describe curses actions. See section "ALTERNATE
+ CONFIGURATIONS" below.
+
+ The ncurses package supports: overall screen, window and pad
+ manipulation; output to windows and pads; reading terminal input;
+ control over terminal and curses input and output options; environment
+ query routines; color manipulation; use of soft label keys; terminfo
+ capabilities; and access to low-level terminal-manipulation routines.
- The library uses the locale which the calling program has initialized.
- That is normally done with setlocale:
+ The library uses the locale which the calling program has initialized.
+ That is normally done with setlocale(3):
setlocale(LC_ALL,"");
- If the locale is not initialized, the library assumes that characters
- are printable as in ISO-8859-1, to work with certain legacy programs.
- You should initialize the locale and not rely on specific details of
- the library when the locale has not been setup.
+ If the locale is not initialized, the library assumes that characters
+ are printable as in ISO-8859-1, to work with certain legacy programs.
+ You should initialize the locale and not rely on specific details of
+ the library when the locale has not been set up.
- The function initscr or newterm must be called to initialize the
- library before any of the other routines that deal with windows and
- screens are used. The routine endwin(3x) must be called before exit-
- ing.
+ The function initscr or newterm must be called to initialize the
+ library before any of the other routines that deal with windows and
+ screens are used. The routine endwin(3x) must be called before
+ exiting.
- To get character-at-a-time input without echoing (most interactive,
- screen oriented programs want this), the following sequence should be
+ To get character-at-a-time input without echoing (most interactive,
+ screen oriented programs want this), the following sequence should be
used:
initscr();cbreak();noecho();
Most programs would additionally use the sequence:
- nonl();intrflush(stdscr,FALSE);keypad(stdscr,TRUE);
Before a curses program is run, the tab stops of the terminal should be
- set and its initialization strings, if defined, must be output. This
- can be done by executing the tputinit command after the shell environ-
- ment variable TERM has been exported. tset(1) is usually responsible
- for doing this. [See terminfo(5) for further details.]
-
-
-
- The ncurses library permits manipulation of data structures, called
- windows, which can be thought of as two-dimensional arrays of charac-
- ters representing all or part of a CRT screen. A default window called
- stdscr, which is the size of the terminal screen, is supplied. Others
- may be created with newwin.
-
- Note that curses does not handle overlapping windows, that's done by
- the panel(3x) library. This means that you can either use stdscr or
- divide the screen into tiled windows and not using stdscr at all. Mix-
- ing the two will result in unpredictable, and undesired, effects.
-
- Windows are referred to by variables declared as WINDOW*. These data
- structures are manipulated with routines described here and elsewhere
- in the ncurses manual pages. Among those, the most basic routines are
- move and addch. More general versions of these routines are included
- with names beginning with w, allowing the user to specify a window.
- The routines not beginning with w affect stdscr.
-
- After using routines to manipulate a window, refresh(3x) is called,
- telling curses to make the user's CRT screen look like stdscr. The
- characters in a window are actually of type chtype, (character and
- attribute data) so that other information about the character may also
- be stored with each character.
+ set and its initialization strings, if defined, must be output. This
+ can be done by executing the tputinit command after the shell
+ environment variable TERM has been exported. (The BSD-style tset(1)
+ utility also performs this function.) See subsection "Tabs and
+ Initialization" of terminfo(5).
+
+
+
+ A curses library abstracts the terminal screen by representing all or
+ part of it as a WINDOW data structure. A window is a rectangular grid
+ of character cells, addressed by row and column coordinates (y, x),
+ with the upper left corner as (0, 0). A window called stdscr, the same
+ size as the terminal screen, is always available. Create others with
+ newwin(3x).
+
+ A curses library does not manage overlapping windows. (See panel(3x)
+ if you desire this.) You can either use stdscr to manage one screen-
+ filling window, or tile the screen into non-overlapping windows and not
+ use stdscr at all. Mixing the two approaches will result in
+ unpredictable, and undesired, effects.
+
+ Functions permit manipulation of a window and the cursor identifying
+ the cell within it at which the next output operation will occur.
+ Among those, the most basic are move(3x) and addch(3x): these place the
+ cursor and write a character to stdscr, respectively. As a rule,
+ window-addressing functions feature names prefixed (or infixed, see
+ below) with "w"; these allow the user to specify a pointer to a WINDOW.
+ Counterparts not thus prefixed (or infixed) affect stdscr. Because
+ moving the cursor prior to another operation is so common, curses
+ generally also provides functions with a "mv" prefix as a convenience.
+ Thus, the library defines all of addch, waddch, mvaddch, and mvwaddch.
+ When both prefixes are present, the order of arguments is a WINDOW
+ pointer first, then a y and x coordinate pair.
+
+ Updating the terminal screen with every curses call can cause
+ unpleasant flicker or inefficient use of the communications channel to
+ the device. Therefore, after using curses functions to accumulate a
+ set of desired updates that make sense to present together, call
+ refresh(3x) to tell the library to make the user's screen look like
+ stdscr. ncursesoptimizes its output by computing a minimal number of
+ operations to mutate the screen from its state at the previous refresh
+ to the new one. Effective optimization demands accurate information
+ about the terminal device: the management of such information is the
+ province of the terminfo(3x) API, a feature of every standard curses
+ implementation.
Special windows called pads may also be manipulated. These are windows
- which are not constrained to the size of the screen and whose contents
- need not be completely displayed. See curs_pad(3x) for more informa-
- tion.
-
- In addition to drawing characters on the screen, video attributes and
- colors may be supported, causing the characters to show up in such
- modes as underlined, in reverse video, or in color on terminals that
- support such display enhancements. Line drawing characters may be
- specified to be output. On input, curses is also able to translate
- arrow and function keys that transmit escape sequences into single val-
- ues. The video attributes, line drawing characters, and input values
- use names, defined in <curses.h>, such as A_REVERSE, ACS_HLINE, and
- KEY_LEFT.
-
-
-
- If the environment variables LINES and COLUMNS are set, or if the pro-
- gram is executing in a window environment, line and column information
- in the environment will override information read by terminfo. This
- would affect a program running in an AT&T 630 layer, for example, where
- the size of a screen is changeable (see ENVIRONMENT).
-
- If the environment variable TERMINFO is defined, any program using
- curses checks for a local terminal definition before checking in the
- standard place. For example, if TERM is set to att4424, then the com-
- piled terminal definition is found in
-
- /usr/share/terminfo/a/att4424.
-
- (The a is copied from the first letter of att4424 to avoid creation of
- huge directories.) However, if TERMINFO is set to $HOME/myterms,
- curses first checks
-
- $HOME/myterms/a/att4424,
-
- and if that fails, it then checks
-
- /usr/share/terminfo/a/att4424.
-
- This is useful for developing experimental definitions or when write
- permission in /usr/share/terminfo is not available.
-
- The integer variables LINES and COLS are defined in <curses.h> and will
- be filled in by initscr with the size of the screen. The constants
- TRUE and FALSE have the values 1 and 0, respectively.
-
- The curses routines also define the WINDOW* variable curscr which is
- used for certain low-level operations like clearing and redrawing a
- screen containing garbage. The curscr can be used in only a few rou-
- tines.
-
-
-
- Many curses routines have two or more versions. The routines prefixed
- with w require a window argument. The routines prefixed with p require
- a pad argument. Those without a prefix generally use stdscr.
-
- The routines prefixed with mv require a y and x coordinate to move to
- before performing the appropriate action. The mv routines imply a call
- to move before the call to the other routine. The coordinate y always
- refers to the row (of the window), and x always refers to the column.
- The upper left-hand corner is always (0,0), not (1,1).
-
- The routines prefixed with mvw take both a window argument and x and y
- coordinates. The window argument is always specified before the coor-
- dinates.
-
- In each case, win is the window affected, and pad is the pad affected;
- win and pad are always pointers to type WINDOW.
-
- Option setting routines require a Boolean flag bf with the value TRUE
- or FALSE; bf is always of type bool. Most of the data types used in
- the library routines, such as WINDOW, SCREEN, bool, and chtype are
- defined in <curses.h>. Types used for the terminfo routines such as
- TERMINAL are defined in <term.h>.
-
- This manual page describes functions which may appear in any configura-
- tion of the library. There are two common configurations of the
- library:
-
- ncurses
- the "normal" library, which handles 8-bit characters. The nor-
- mal (8-bit) library stores characters combined with attributes
- in chtype data.
-
- Attributes alone (no corresponding character) may be stored in
- chtype or the equivalent attr_t data. In either case, the data
- is stored in something like an integer.
-
- Each cell (row and column) in a WINDOW is stored as a chtype.
-
- ncursesw
- the so-called "wide" library, which handles multibyte charac-
- ters (see the section on ALTERNATECONFIGURATIONS). The "wide"
- library includes all of the calls from the "normal" library.
- It adds about one third more calls using data types which store
- multibyte characters:
-
- cchar_t
- corresponds to chtype. However it is a structure, because
- more data is stored than can fit into an integer. The
- characters are large enough to require a full integer
- value - and there may be more than one character per cell.
- The video attributes and color are stored in separate
- fields of the structure.
-
- Each cell (row and column) in a WINDOW is stored as a
- cchar_t.
-
- wchar_t
- stores a "wide" character. Like chtype, this may be an
- integer.
-
- wint_t
- stores a wchar_t or WEOF - not the same, though both may
- have the same size.
-
- The "wide" library provides new functions which are analogous
- to functions in the "normal" library. There is a naming con-
- vention which relates many of the normal/wide variants: a "_w"
- is inserted into the name. For example, waddch becomes
- wadd_wch.
-
-
-
- The following table lists each curses routine and the name of the man-
- ual page on which it is described. Routines flagged with "*" are
- ncurses-specific, not described by XPG4 or present in SVr4.
-
- curses Routine Name Manual Page Name
+ that are not constrained to the size of the terminal screen and whose
+ contents need not be completely displayed. See curs_pad(3x).
+
+ In addition to drawing characters on the screen, rendering attributes
+ and colors may be supported, causing the characters to show up in such
+ modes as underlined, in reverse video, or in color on terminals that
+ support such display enhancements. See curs_attr(3x).
+
+ curses predefines constants for a small set of line-drawing and other
+ graphics corresponding to the DEC Alternate Character Set (ACS), a
+ feature of VT100 and other terminals. See waddch(3x) and wadd_wch(3x).
+
+ curses is implemented using the operating system's terminal driver;
+ keystroke events are received not as scan codes but as byte sequences.
+ Graphical keycaps (alphanumeric and punctuation keys, and the space)
+ appear as-is. Everything else, including the tab, enter/return,
+ keypad, arrow, and function keys, appears as a control character or a
+ multibyte escapesequence.curses translates these into unique key
+ codes. See getch(3x).
+
+
+
+ The selection of an appropriate value of TERM in the process
+ environment is essential to correct curses and terminfo library
+ operation. A well-configured system selects a correct TERM value
+ automatically; tset(1) may assist with troubleshooting exotic
+ situations.
+
+ If the environment variables LINES and COLUMNS are set, or if the
+ curses program is executing in a graphical windowing environment, the
+ information obtained thence overrides that obtained by terminfo. An
+ ncurses extension supports resizable terminals; see wresize(3x).
+
+ If the environment variable TERMINFO is defined, a curses program
+ checks first for a terminal type description in the location it
+ identifies. TERMINFO is useful for developing experimental type
+ descriptions or when write permission to /usr/share/terminfo is not
+ available.
+
+ See section "ENVIRONMENT" below.
+
+
+
+ Many curses functions have two or more versions. Those prefixed with
+ "w" require a window argument. Four functions prefixed with "p"
+ require a pad argument. Those without a prefix generally operate on
+ stdscr.
+
+ In function synopses, ncurses man pages apply the following names to
+ parameters.
+
+ bfbool (TRUE or FALSE)
+ win pointer to WINDOW
+ pad pointer to WINDOW that is a pad
+
+
+
+ This manual page describes functions that appear in any configuration
+ of the library. There are two common configurations; see section
+ "ALTERNATE CONFIGURATIONS" below.
+
+ ncurses is the library in its "non-wide" configuration, handling only
+ eight-bit characters. It stores a character combined with
+ attributes in a chtype datum, which is often an alias of int.
+
+ Attributes alone (with no corresponding character) can be
+ stored in variables of chtype or attr_t type. In either
+ case, they are represented as an integral bit mask.
+
+ Each cell of a WINDOW is stored as a chtype.
+
+ ncursesw is the library in its "wide" configuration, which handles
+ character encodings requiring a larger data type than char (a
+ byte-sized type) can represent. It adds about one third more
+ calls using additional data types that can store such
+ multibyte characters.
+
+ cchar_t corresponds to the non-wide configuration's chtype.
+ It always a structure type, because it stores more
+ data than fits into an integral type. A character
+ code may not be representable as a char, and
+ moreover more than one character may occupy a cell
+ (as with accent marks and other diacritics). Each
+ character is of type wchar_t; a complex character
+ contains one spacing character and zero or more non-
+ spacing characters (see below). Attributes and
+ color data are stored in separate fields of the
+ structure, not combined as in chtype.
+
+ Each cell of a WINDOW is stored as a cchar_t.
+
+ The setcchar(3x) and getcchar(3x) functions store and
+ retrieve the data from a cchar_t structure. The wide library
+ API of ncurses depends on two data types standardized by ISO
+ C95.
+
+ wchar_t stores a wide character. Like chtype, it may be an
+ alias of int. Depending on the character encoding,
+ a wide character may be spacing, meaning that it
+ occupies a character cell by itself and typically
+ accompanies cursor advancement, or non-spacing,
+ meaning that it occupies the same cell as a spacing
+ character, is often regarded as a "modifier" of the
+ base glyph with which it combines, and typically
+ does not advance the cursor.
+
+ wint_t can store a wchar_t or the constant WEOF,
+ analogously to the int-sized character manipulation
+ functions of ISO C and its constant EOF.
+
+ The wide library provides additional functions that
+ complement those in the non-wide library where the size of
+ the underlying character type is significant. A somewhat
+ regular naming convention relates many of the wide variants
+ to their non-wide counterparts; where a non-wide function
+ name contains "ch" or "str", prefix it with "_w" to obtain
+ the wide counterpart. For example, waddch becomes wadd_wch.
+
+ This convention is inapplicable to some non-wide function
+ names, so other transformations are used for the wide
+ configuration: in the window background management functions,
+ "bkgd" becomes "bkgrnd"; the window border-drawing and
+ -clearing functions are suffixed with "_set".
+
+
+
- Routines that return an integer return ERR upon failure and an integer
- value other than ERR upon successful completion, unless otherwise noted
- in the routine descriptions.
+ curs_memleaks(3x) - curses memory-leak checking
- As a general rule, routines check for null pointers passed as parame-
- ters, and handle this as an error.
+ curs_sp_funcs(3x) - curses screen-pointer extension
- All macros return the value of the w version, except setscrreg,
- wsetscrreg, getyx, getbegyx, and getmaxyx. The return values of
- setscrreg, wsetscrreg, getyx, getbegyx, and getmaxyx are undefined
- (i.e., these should not be used as the right-hand side of assignment
- statements).
+ curs_threads(3x) - curses thread support
- Routines that return pointers return NULL on error.
+ curs_trace(3x) - curses debugging routines
+
+
+
+ Unless otherwise noted, functions that return an integer return OK on
+ success and ERR on failure. Functions that return pointers return NULL
+ on failure. Typically, ncurses treats a null pointer passed as a
+ function parameter as a failure.
+
+ Functions with a "mv" prefix first perform cursor movement using wmove
+ and fail if the position is outside the window, or (for "mvw"
+ functions) if the WINDOW pointer is null.
- The following environment symbols are useful for customizing the run-
- time behavior of the ncurses library. The most important ones have
+ The following environment symbols are useful for customizing the
+ runtime behavior of the ncurses library. The most important ones have
been already discussed in detail.
-
- When set, change occurrences of the command_character (i.e., the cmdch
- capability) of the loaded terminfo entries to the value of this vari-
- able. Very few terminfo entries provide this feature.
+
+ When set, change the command_character (cmdch) capability value of
+ loaded terminfo entries to the value of this variable. Very few term-
+ info entries provide this feature.
Because this name is also used in development environments to represent
- the C compiler's name, ncurses ignores it if it does not happen to be a
+ the C compiler's name, ncurses ignores it if it does not happen to be a
single character.
-
- The debugging library checks this environment variable when the appli-
- cation has redirected output to a file. The variable's numeric value
- is used for the baudrate. If no value is found, ncurses uses 9600.
- This allows testers to construct repeatable test-cases that take into
- account costs that depend on baudrate.
+
+ The debugging library checks this environment variable when the
+ application has redirected output to a file. The variable's numeric
+ value is used for the baud rate. If no value is found, ncurses uses
+ 9600. This allows testers to construct repeatable test-cases that take
+ into account costs that depend on baud rate.
-
Specify the width of the screen in characters. Applications running in
a windowing environment usually are able to obtain the width of the
- window in which they are executing. If neither the COLUMNS value nor
- the terminal's screen size is available, ncurses uses the size which
+ window in which they are executing. If neither the COLUMNS value nor
+ the terminal's screen size is available, ncurses uses the size which
may be specified in the terminfo database (i.e., the cols capability).
It is important that your application use a correct size for the
screen. This is not always possible because your application may be
running on a host which does not honor NAWS (Negotiations About Window
- Size), or because you are temporarily running as another user. How-
- ever, setting COLUMNS and/or LINES overrides the library's use of the
- screen size obtained from the operating system.
+ Size), or because you are temporarily running as another user.
+ However, setting COLUMNS and/or LINES overrides the library's use of
+ the screen size obtained from the operating system.
- Either COLUMNS or LINES symbols may be specified independently. This
- is mainly useful to circumvent legacy misfeatures of terminal descrip-
- tions, e.g., xterm which commonly specifies a 65 line screen. For best
- results, lines and cols should not be specified in a terminal descrip-
- tion for terminals which are run as emulations.
+ Either COLUMNS or LINES symbols may be specified independently. This
+ is mainly useful to circumvent legacy misfeatures of terminal
+ descriptions, e.g., xterm which commonly specifies a 65 line screen.
+ For best results, lines and cols should not be specified in a terminal
+ description for terminals which are run as emulations.
Use the use_env function to disable all use of external environment
(but not including system calls) to determine the screen size. Use the
- use_tioctl function to update COLUMNS or LINES to match the screen size
+ use_tioctl function to update COLUMNS or LINES to match the screen size
obtained from system calls or the terminal database.
-
+ Specifies the total time, in milliseconds, for which ncurses will await
a character sequence, e.g., a function key. The default value, 1000
milliseconds, is enough for most uses. However, it is made a variable
to accommodate unusual applications.
@@ -819,93 +860,93 @@
still see a timeout.
Note that xterm mouse events are built up from character sequences
- received from the xterm. If your application makes heavy use of multi-
- ple-clicking, you may wish to lengthen this default value because the
- timeout applies to the composed multi-click event as well as the indi-
- vidual clicks.
+ received from the xterm. If your application makes heavy use of
+ multiple-clicking, you may wish to lengthen this default value because
+ the timeout applies to the composed multi-click event as well as the
+ individual clicks.
In addition to the environment variable, this implementation provides a
global variable with the same name. Portable applications should not
- rely upon the presence of ESCDELAY in either form, but setting the
+ rely upon the presence of ESCDELAY in either form, but setting the
environment variable rather than the global variable does not create
problems when compiling an application.
-
- This applies only to the OS/2 EMX port. It specifies the order of but-
- tons on the mouse. OS/2 numbers a 3-button mouse inconsistently from
- other platforms:
+
+ This applies only to the OS/2 EMX port. It specifies the order of
+ buttons on the mouse. OS/2 numbers a 3-button mouse inconsistently
+ from other platforms:
1 = left
2 = right
3 = middle.
This variable lets you customize the mouse. The variable must be three
- numeric digits 1-3 in any order, e.g., 123 or 321. If it is not speci-
- fied, ncurses uses 132.
+ numeric digits 1-3 in any order, e.g., 123 or 321. If it is not
+ specified, ncurses uses 132.
-
Override the compiled-in assumption that the terminal's default colors
- are white-on-black (see default_colors(3x)). You may set the fore-
- ground and background color values with this environment variable by
- proving a 2-element list: foreground,background. For example, to tell
- ncurses to not assume anything about the colors, set this to "-1,-1".
- To make it green-on-black, set it to "2,0". Any positive value from
- zero to the terminfo max_colors value is allowed.
+ are white-on-black (see default_colors(3x)). You may set the
+ foreground and background color values with this environment variable
+ by proving a 2-element list: foreground,background. For example, to
+ tell ncurses to not assume anything about the colors, set this to
+ "-1,-1". To make it green-on-black, set it to "2,0". Any positive
+ value from zero to the terminfo max_colors value is allowed.
-
+ This applies only to the MinGW port of ncurses.
- The Console2 program's handling of the Microsoft Console API call Cre-
- ateConsoleScreenBuffer is defective. Applications which use this will
- hang. However, it is possible to simulate the action of this call by
- mapping coordinates, explicitly saving and restoring the original
+ The Console2 program's handling of the Microsoft Console API call
+ CreateConsoleScreenBuffer is defective. Applications which use this
+ will hang. However, it is possible to simulate the action of this call
+ by mapping coordinates, explicitly saving and restoring the original
screen contents. Setting the environment variable NCGDB has the same
effect.
-
+ This applies only to ncurses configured to use the GPM interface.
If present, the environment variable is a list of one or more terminal
- names against which the TERM environment variable is matched. Setting
+ names against which the TERM environment variable is matched. Setting
it to an empty value disables the GPM interface; using the built-in
support for xterm, etc.
- If the environment variable is absent, ncurses will attempt to open GPM
- if TERM contains "linux".
+ If the environment variable is absent, ncurses will attempt to open GPM
+ if TERM contains "linux".
-
- Ncurses may use tabs as part of the cursor movement optimization. In
- some cases, your terminal driver may not handle these properly. Set
- this environment variable to disable the feature. You can also adjust
- your stty settings to avoid the problem.
+
+ ncurses may use tabs as part of cursor movement optimization. In some
+ cases, your terminal driver may not handle these properly. Set this
+ environment variable to any value to disable the feature. You can also
+ adjust your stty(1) settings to avoid the problem.
-
- Some terminals use a magic-cookie feature which requires special han-
- dling to make highlighting and other video attributes display properly.
- You can suppress the highlighting entirely for these terminals by set-
- ting this environment variable.
+
+ Some terminals use a magic-cookie feature which requires special
+ handling to make highlighting and other video attributes display
+ properly. You can suppress the highlighting entirely for these
+ terminals by setting this environment variable to any value.
-
Most of the terminal descriptions in the terminfo database are written
for real "hardware" terminals. Many people use terminal emulators
which run in a windowing environment and use curses-based applications.
@@ -914,64 +955,64 @@
chief limitation of a hardware terminal from the standpoint of your
application is the management of dataflow, i.e., timing. Unless a
hardware terminal is interfaced into a terminal concentrator (which
- does flow control), it (or your application) must manage dataflow, pre-
- venting overruns. The cheapest solution (no hardware cost) is for your
- program to do this by pausing after operations that the terminal does
- slowly, such as clearing the display.
+ does flow control), it (or your application) must manage dataflow,
+ preventing overruns. The cheapest solution (no hardware cost) is for
+ your program to do this by pausing after operations that the terminal
+ does slowly, such as clearing the display.
As a result, many terminal descriptions (including the vt100) have
delay times embedded. You may wish to use these descriptions, but not
want to pay the performance penalty.
- Set the NCURSES_NO_PADDING environment variable to disable all but
- mandatory padding. Mandatory padding is used as a part of special con-
- trol sequences such as flash.
+ Set the NCURSES_NO_PADDING environment variable to disable all but
+ mandatory padding. Mandatory padding is used as a part of special
+ control sequences such as flash.
-
This setting is obsolete. Before changes
o started with 5.9 patch 20120825 and
o continued though 5.9 patch 20130126
- ncurses enabled buffered output during terminal initialization. This
- was done (as in SVr4 curses) for performance reasons. For testing pur-
- poses, both of ncurses and certain applications, this feature was made
- optional. Setting the NCURSES_NO_SETBUF variable disabled output
+ ncurses enabled buffered output during terminal initialization. This
+ was done (as in SVr4 curses) for performance reasons. For testing
+ purposes, both of ncurses and certain applications, this feature was
+ made optional. Setting the NCURSES_NO_SETBUF variable disabled output
buffering, leaving the output in the original (usually line buffered)
mode.
- In the current implementation, ncurses performs its own buffering and
+ In the current implementation, ncurses performs its own buffering and
does not require this workaround. It does not modify the buffering of
the standard output.
The reason for the change was to make the behavior for interrupts and
- other signals more robust. One drawback is that certain nonconven-
- tional programs would mix ordinary stdio calls with ncurses calls and
- (usually) work. This is no longer possible since ncurses is not using
- the buffered standard output but its own output (to the same file
- descriptor). As a special case, the low-level calls such as putp still
- use the standard output. But high-level curses calls do not.
+ other signals more robust. One drawback is that certain
+ nonconventional programs would mix ordinary stdio(3) calls with ncurses
+ calls and (usually) work. This is no longer possible since ncurses is
+ not using the buffered standard output but its own output (to the same
+ file descriptor). As a special case, the low-level calls such as putp
+ still use the standard output. But high-level curses calls do not.
-
+ During initialization, the ncurses library checks for special cases
where VT100 line-drawing (and the corresponding alternate character set
capabilities) described in the terminfo are known to be missing.
- Specifically, when running in a UTF-8 locale, the Linux console emula-
- tor and the GNU screen program ignore these. Ncurses checks the TERM
- environment variable for these. For other special cases, you should
- set this environment variable. Doing this tells ncurses to use Unicode
- values which correspond to the VT100 line-drawing glyphs. That works
- for the special cases cited, and is likely to work for terminal emula-
- tors.
-
- When setting this variable, you should set it to a nonzero value. Set-
- ting it to zero (or to a nonnumber) disables the special check for
+ Specifically, when running in a UTF-8 locale, the Linux console
+ emulator and the GNU screen program ignore these. ncurseschecksthe
+ TERMenvironmentvariableforthese.Forotherspecialcases,you
+ shouldsetthisenvironmentvariable.Doingthistellsncursestouse
+ UnicodevalueswhichcorrespondtotheVT100line-drawingglyphs.That
+ worksforthespecialcasescited,andislikelytoworkforterminal
+ emulators.
+
+ When setting this variable, you should set it to a nonzero value.
+ Setting it to zero (or to a nonnumber) disables the special check for
"linux" and "screen".
- As an alternative to the environment variable, ncurses checks for an
+ As an alternative to the environment variable, ncurses checks for an
extended terminfo capability U8. This is a numeric capability which
can be compiled using tic-x. For example
@@ -985,55 +1026,55 @@
U8#1, use=xterm,
The name "U8" is chosen to be two characters, to permit it to be used
- by applications that use ncurses' termcap interface.
+ by applications that use ncurses' termcap interface.
-
- During initialization, the ncurses debugging library checks the
- NCURSES_TRACE environment variable. If it is defined, to a numeric
- value, ncurses calls the trace function, using that value as the argu-
- ment.
+
+ During initialization, the ncurses debugging library checks the
+ NCURSES_TRACE environment variable. If it is defined, to a numeric
+ value, ncurses calls the trace function, using that value as the
+ argument.
The argument values, which are defined in curses.h, provide several
- types of information. When running with traces enabled, your applica-
- tion will write the file trace to the current directory.
+ types of information. When running with traces enabled, your
+ application will write the file trace to the current directory.
See curs_trace(3x) for more information.
-
Denotes your terminal type. Each terminal type is distinct, though
many are similar.
- TERM is commonly set by terminal emulators to help applications find a
- workable terminal description. Some of those choose a popular approxi-
- mation, e.g., "ansi", "vt100", "xterm" rather than an exact fit. Not
- infrequently, your application will have problems with that approach,
- e.g., incorrect function-key definitions.
+ TERM is commonly set by terminal emulators to help applications find a
+ workable terminal description. Some of those choose a popular
+ approximation, e.g., "ansi", "vt100", "xterm" rather than an exact fit.
+ Not infrequently, your application will have problems with that
+ approach, e.g., incorrect function-key definitions.
- If you set TERM in your environment, it has no effect on the operation
+ If you set TERM in your environment, it has no effect on the operation
of the terminal emulator. It only affects the way applications work
- within the terminal. Likewise, as a general rule (xterm being a rare
- exception), terminal emulators which allow you to specify TERM as a
- parameter or configuration value do not change their behavior to match
- that setting.
+ within the terminal. Likewise, as a general rule (xterm(1) being a
+ rare exception), terminal emulators which allow you to specify TERM as
+ a parameter or configuration value do not change their behavior to
+ match that setting.
-
+ If the ncurses library has been configured with termcap support,
+ ncurses will check for a terminal's description in termcap form if it
is not available in the terminfo database.
- The TERMCAP environment variable contains either a terminal description
- (with newlines stripped out), or a file name telling where the informa-
- tion denoted by the TERM environment variable exists. In either case,
- setting it directs ncurses to ignore the usual place for this informa-
- tion, e.g., /etc/termcap.
+ The TERMCAP environment variable contains either a terminal description
+ (with newlines stripped out), or a file name telling where the
+ information denoted by the TERM environment variable exists. In either
+ case, setting it directs ncurses to ignore the usual place for this
+ information, e.g., /etc/termcap.
-
+ ncurses can be configured to read from multiple terminal databases.
+ The TERMINFO variable overrides the location for the default terminal
database. Terminal descriptions (in terminal format) are stored in
terminal databases:
@@ -1041,10 +1082,10 @@
named by the first letter of the terminal names therein.
This is the scheme used in System V, which legacy Unix systems use,
- and the TERMINFO variable is used by curses applications on those
+ and the TERMINFO variable is used by curses applications on those
systems to override the default location of the terminal database.
- o If ncurses is built to use hashed databases, then each entry in
+ o If ncurses is built to use hashed databases, then each entry in
this list may be the path of a hashed database file, e.g.,
/usr/share/terminfo.db
@@ -1058,11 +1099,11 @@
existence of the directory tree, reading it directly rather than
using the terminfo library calls.
- o If ncurses is built with a support for reading termcap files
+ o If ncurses is built with a support for reading termcap files
directly, then an entry in this list may be the path of a termcap
file.
- o If the TERMINFO variable begins with "hex:" or "b64:", ncurses uses
+ o If the TERMINFO variable begins with "hex:" or "b64:", ncurses uses
the remainder of that variable as a compiled terminal description.
You might produce the base64 format using infocmp(1m):
@@ -1070,46 +1111,46 @@
export TERMINFO
The compiled description is used if it corresponds to the terminal
- identified by the TERM variable.
+ identified by the TERM variable.
- Setting TERMINFO is the simplest, but not the only way to set location
- of the default terminal database. The complete list of database loca-
- tions in order follows:
+ Setting TERMINFO is the simplest, but not the only way to set location
+ of the default terminal database. The complete list of database
+ locations in order follows:
- o the last terminal database to which ncurses wrote, if any, is
+ o the last terminal database to which ncurses wrote, if any, is
searched first
- o the location specified by the TERMINFO environment variable
+ o the location specified by the TERMINFO environment variable
o $HOME/.terminfo
- o locations listed in the TERMINFO_DIRS environment variable
+ o locations listed in the TERMINFO_DIRS environment variable
o one or more locations whose names are configured and compiled
- into the ncurses library, i.e.,
+ into the ncurses library, i.e.,
- o /usr/local/ncurses/share/terminfo:/usr/share/terminfo (corre-
- sponding to the TERMINFO_DIRS variable)
+ o /usr/share/terminfo (corresponding to the TERMINFO_DIRS
+ variable)
- o /usr/share/terminfo (corresponding to the TERMINFO variable)
+ o /usr/share/terminfo (corresponding to the TERMINFO variable)
-
Specifies a list of locations to search for terminal descriptions.
Each location in the list is a terminal database as described in the
- section on the TERMINFO variable. The list is separated by colons
+ section on the TERMINFO variable. The list is separated by colons
(i.e., ":") on Unix, semicolons on OS/2 EMX.
- There is no corresponding feature in System V terminfo; it is an exten-
- sion developed for ncurses.
+ There is no corresponding feature in System V terminfo; it is an
+ extension developed for ncurses.
-
+ If TERMCAP does not hold a file name then ncurses checks the TERMPATH
environment variable. This is a list of filenames separated by spaces
or colons (i.e., ":") on Unix, semicolons on OS/2 EMX.
- If the TERMPATH environment variable is not set, ncurses looks in the
+ If the TERMPATH environment variable is not set, ncurses looks in the
files
/etc/termcap, /usr/share/misc/termcap and $HOME/.termcap,
@@ -1124,20 +1165,20 @@
- Several different configurations are possible, depending on the config-
- ure script options used when building ncurses. There are a few main
- options whose effects are visible to the applications developer using
- ncurses:
+ Many different ncurses configurations are possible, determined by the
+ options given to the configure script when building the library. Run
+ the script with the --help option to peruse them all. A few are of
+ particular significance to the application developer employing ncurses.
--disable-overwrite
- The standard include for ncurses is as noted in SYNOPSIS:
+ The standard include for ncurses is as noted in SYNOPSIS:
#include<curses.h>
- This option is used to avoid filename conflicts when ncurses is
- not the main implementation of curses of the computer. If ncurses
- is installed disabling overwrite, it puts its headers in a subdi-
- rectory, e.g.,
+ This option is used to avoid filename conflicts when ncurses is
+ not the main implementation of curses of the computer. If ncurses
+ is installed disabling overwrite, it puts its headers in a
+ subdirectory, e.g.,
#include<ncurses/curses.h>
@@ -1145,10 +1186,10 @@
-lcurses to build executables.
--enable-widec
- The configure script renames the library and (if the --dis-
- able-overwrite option is used) puts the header files in a differ-
- ent subdirectory. All of the library names have a "w" appended to
- them, i.e., instead of
+ The configure script renames the library and (if the
+ --disable-overwrite option is used) puts the header files in a
+ different subdirectory. All of the library names have a "w"
+ appended to them, i.e., instead of
-lncurses
@@ -1177,15 +1218,15 @@
than curses.h may require a specific value for _XOPEN_SOURCE
(or a system-specific symbol).
- The curses.h file which is installed for the wide-character
- library is designed to be compatible with the normal library's
- header. Only the size of the WINDOW structure differs, and very
- few applications require more than a pointer to WINDOWs.
+ The curses.h header file installed for the wide-character library
+ is designed to be compatible with the non-wide library's header.
+ Only the size of the WINDOW structure differs; few applications
+ require more than pointers to WINDOWs.
- If the headers are installed allowing overwrite, the wide-charac-
- ter library's headers should be installed last, to allow applica-
- tions to be built using either library from the same set of head-
- ers.
+ If the headers are installed allowing overwrite, the wide-
+ character library's headers should be installed last, to allow
+ applications to be built using either library from the same set of
+ headers.
--with-pthread
The configure script renames the library. All of the library
@@ -1204,138 +1245,261 @@
--with-debug
--with-profile
- The shared and normal (static) library names differ by their suf-
- fixes, e.g., libncurses.so and libncurses.a. The debug and pro-
- filing libraries add a "_g" and a "_p" to the root names respec-
- tively, e.g., libncurses_g.a and libncurses_p.a.
+ The shared and normal (static) library names differ by their
+ suffixes, e.g., libncurses.so and libncurses.a. The debug and
+ profiling libraries add a "_g" and a "_p" to the root names
+ respectively, e.g., libncurses_g.a and libncurses_p.a.
+
+ --with-termlib
+ Low-level functions which do not depend upon whether the library
+ supports wide-characters, are provided in the tinfo library.
+
+ By doing this, it is possible to share the tinfo library between
+ wide/normal configurations as well as reduce the size of the
+ library when only low-level functions are needed.
+
+ Those functions are described in these pages:
+
+ ocurs_extend(3x) - miscellaneous curses extensions
+
+ ocurs_inopts(3x) - curses input options
+
+ ocurs_kernel(3x) - low-level curses routines
+
+ ocurs_termattrs(3x) - curses environment query routines
+
+ ocurs_termcap(3x) - curses emulation of termcap
+
+ ocurs_terminfo(3x) - curses interface to terminfo database
+
+ ocurs_util(3x) - miscellaneous curses utility routines
--with-trace
- The trace function normally resides in the debug library, but it
- is sometimes useful to configure this in the shared library. Con-
- figure scripts should check for the function's existence rather
+ The trace function normally resides in the debug library, but it
+ is sometimes useful to configure this in the shared library.
+ Configure scripts should check for the function's existence rather
than assuming it is always in the debug library.
- terminfo(5) and related pages whose names begin "curs_" for detailed
- routine descriptions.
- curs_variables(3x)
- user_caps(5) for user-defined capabilities
+
+
+ X/Open Curses permits most functions it specifies to be made available
+ as macros as well. ncurses does so
+
+ o for functions that return values via their parameters,
+
+ o to support obsolete features,
+
+ o to reuse functions (for example, those that move the cursor before
+ another operation), and
+
+ o a few special cases.
+
+ If the standard output file descriptor of an ncurses program is
+ redirected to something that is not a terminal device, the library
+ writes screen updates to the standard error file descriptor. This was
+ an undocumented feature of SVr3.
+
+ See subsection "Header files" below regarding symbols exposed by
+ inclusion of curses.h.
- The ncurses library can be compiled with an option (-DUSE_GETCAP) that
- falls back to the old-style /etc/termcap file if the terminal setup
- code cannot find a terminfo entry corresponding to TERM. Use of this
- feature is not recommended, as it essentially includes an entire term-
- cap compiler in the ncurses startup code, at significant cost in core
- and startup cycles.
-
- The ncurses library includes facilities for capturing mouse events on
- certain terminals (including xterm). See the curs_mouse(3x) manual
- page for details.
-
- The ncurses library includes facilities for responding to window resiz-
- ing events, e.g., when running in an xterm. See the resizeterm(3x) and
- wresize(3x) manual pages for details. In addition, the library may be
- configured with a SIGWINCH handler.
-
- The ncurses library extends the fixed set of function key capabilities
- of terminals by allowing the application designer to define additional
- key sequences at runtime. See the define_key(3x)key_defined(3x), and
- keyok(3x) manual pages for details.
-
- The ncurses library can exploit the capabilities of terminals which
- implement the ISO-6429 SGR 39 and SGR 49 controls, which allow an
- application to reset the terminal to its original foreground and back-
- ground colors. From the users' perspective, the application is able to
- draw colored text on a background whose color is set independently,
- providing better control over color contrasts. See the default_col-
- ors(3x) manual page for details.
-
- The ncurses library includes a function for directing application out-
- put to a printer attached to the terminal device. See the
- curs_print(3x) manual page for details.
+ ncurses enables an application to capture mouse events on certain
+ terminals, including xterm; see curs_mouse(3x).
+ ncurses provides a means of responding to window resizing events, as
+ when running in a GUI terminal emulator application such as xterm; see
+ resizeterm(3x) and wresize(3x).
-
- The ncurses library is intended to be BASE-level conformant with XSI
- Curses. The EXTENDED XSI Curses functionality (including color sup-
- port) is supported.
+ ncurses allows an application to query the terminal for the presence of
+ a wide variety of special keys; see has_key(3x).
+
+ ncurses extends the fixed set of function key capabilities specified by
+ X/Open Curses by allowing the application programmer to define
+ additional key sequences at runtime; see define_key(3x),
+ key_defined(3x), and keyok(3x).
- A small number of local differences (that is, individual differences
- between the XSI Curses and ncurses calls) are described in PORTABILITY
- sections of the library man pages.
+ ncurses can exploit the capabilities of terminals implementing
+ ISO 6429/ECMA-48 SGR 39 and SGR 49 sequences, which allow an
+ application to reset the terminal to its original foreground and
+ background colors. From a user's perspective, the application is able
+ to draw colored text on a background whose color is set independently,
+ providing better control over color contrasts. See default_colors(3x).
- Unlike other implementations, this one checks parameters such as point-
- ers to WINDOW structures to ensure they are not null. The main reason
- for providing this behavior is to guard against programmer error. The
- standard interface does not provide a way for the library to tell an
- application which of several possible errors were detected. Relying on
- this (or some other) extension will adversely affect the portability of
- curses applications.
+ An ncurses application can choose to hide the internal details of
+ WINDOW structures, instead using accessor functions such as
+ is_scrollok(3x).
- This implementation also contains several extensions:
+ ncurses enables an application to direct application output to a
+ printer attached to the terminal device; see curs_print(3x).
- o The routine has_key is not part of XPG4, nor is it present in SVr4.
- See the curs_getch(3x) manual page for details.
+ ncurses offers slk_attr(3x) as a counterpart of attr_get(3x) for soft-
+ label key lines, and extended_slk_color(3x) as a form of slk_color(3x)
+ that can gather color information from them when many colors are
+ supported.
- o The routine slk_attr is not part of XPG4, nor is it present in
- SVr4. See the curs_slk(3x) manual page for details.
+ Some extensions are only available if ncurses is compiled to support
+ them; see section "ALTERNATE CONFIGURATIONS" above.
- o The routines getmouse, mousemask, ungetmouse, mouseinterval, and
- wenclose relating to mouse interfacing are not part of XPG4, nor
- are they present in SVr4. See the curs_mouse(3x) manual page for
- details.
+ o Rudimentary support for multi-threaded applications may be
+ available; see curs_threads(3x).
- o The routine mcprint was not present in any previous curses imple-
- mentation. See the curs_print(3x) manual page for details.
+ o Functions that ease the management of multiple screens can be
+ exposed; see curs_sp_funcs(3x).
- o The routine wresize is not part of XPG4, nor is it present in SVr4.
- See the wresize(3x) manual page for details.
+ o The compiler option -DUSE_GETCAP causes the library to fall back to
+ reading /etc/termcap if the terminal setup code cannot find a term-
+ info entry corresponding to TERM. Use of this feature is not
+ recommended, as it essentially includes an entire termcap compiler
+ in the ncurses startup code, at a cost in memory usage and
+ application launch latency.
- o The WINDOW structure's internal details can be hidden from applica-
- tion programs. See curs_opaque(3x) for the discussion of is_scrol-
- lok, etc.
+ PDCurses and NetBSD curses incorporate some ncurses extensions.
+ Individual man pages indicate where this is the case.
+
+
+
+ X/Open Curses defines two levels of conformance, "base" and "enhanced".
+ The latter includes several additional features, such as wide-character
+ and color support. ncurses intends base-level conformance with X/Open
+ Curses, and supports nearly all its enhanced features.
- o This implementation can be configured to provide rudimentary sup-
- port for multi-threaded applications. See curs_threads(3x) for
- details.
+ Differences between X/Open Curses and ncurses are documented in the
+ "PORTABILITY" sections of applicable man pages.
- o This implementation can also be configured to provide a set of
- functions which improve the ability to manage multiple screens.
- See curs_sp_funcs(3x) for details.
- In historic curses versions, delays embedded in the capabilities cr,
- ind, cub1, ff and tab activated corresponding delay bits in the UNIX
+
+ In many cases, X/Open Curses is vague about error conditions, omitting
+ some of the SVr4 documentation.
+
+ Unlike other implementations, this one checks parameters such as
+ pointers to WINDOW structures to ensure they are not null. The main
+ reason for providing this behavior is to guard against programmer
+ error. The standard interface does not provide a way for the library
+ to tell an application which of several possible errors were detected.
+ Relying on this (or some other) extension will adversely affect the
+ portability of curses applications.
+
+
+
+ In historic curses versions, delays embedded in the capabilities cr,
+ ind, cub1, ff and tab activated corresponding delay bits in the Unix
tty driver. In this implementation, all padding is done by sending NUL
- bytes. This method is slightly more expensive, but narrows the inter-
- face to the UNIX kernel significantly and increases the package's
+ bytes. This method is slightly more expensive, but narrows the
+ interface to the Unix kernel significantly and increases the package's
portability correspondingly.
-
+ The header file curses.h itself includes the header files stdio.h and
+ unctrl.h.
+
+ X/Open Curses has more to say, but does not finish the story:
+
+ The inclusion of <curses.h> may make visible all symbols from the
+ headers <stdio.h>, <term.h>, <termios.h>, and <wchar.h>.
+
+ Here is a more complete story:
+
+ o Starting with BSD curses, all implementations have included
+ <stdio.h>.
+
+ BSD curses included <curses.h> and <unctrl.h> from an internal
+ header file curses.ext ("ext" abbreviated "externs").
+
+ BSD curses used <stdio.h> internally (for printw and scanw), but
+ nothing in <curses.h> itself relied upon <stdio.h>.
+
+ o SVr2 curses added newterm(3x), which relies upon <stdio.h>. That
+ is, the function prototype uses FILE.
+
+ SVr4 curses added putwin and getwin, which also use <stdio.h>.
+
+ X/Open Curses documents all three of these functions.
+
+ SVr4 curses and X/Open Curses do not require the developer to
+ include <stdio.h> before including <curses.h>. Both document
+ curses showing <curses.h> as the only required header.
+
+ As a result, standard <curses.h> will always include <stdio.h>.
+
+ o X/Open Curses is inconsistent with respect to SVr4 regarding
+ <unctrl.h>.
- If standard output from a ncurses program is re-directed to something
- which is not a tty, screen updates will be directed to standard error.
- This was an undocumented feature of AT&T System V Release 3 curses.
+ As noted in curs_util(3x), ncurses includes <unctrl.h> from
+ <curses.h> (like SVr4).
+
+ o X/Open's comments about <term.h> and <termios.h> may refer to HP-UX
+ and AIX:
+
+ HP-UX curses includes <term.h> from <curses.h> to declare setupterm
+ in curses.h, but ncurses (and Solaris curses) do not.
+
+ AIX curses includes <term.h> and <termios.h>. Again, ncurses (and
+ Solaris curses) do not.
+
+ o X/Open says that <curses.h> may include <term.h>, but there is no
+ requirement that it do that.
+
+ Some programs use functions declared in both <curses.h> and
+ <term.h>, and must include both headers in the same module. Very
+ old versions of AIX curses required including <curses.h> before
+ including <term.h>.
+
+ Because ncurses header files include the headers needed to define
+ datatypes used in the headers, ncurses header files can be included
+ in any order. But for portability, you should include <curses.h>
+ before <term.h>.
+
+ o X/Open Curses says "maymakevisible" because including a header
+ file does not necessarily make all symbols in it visible (there are
+ ifdef's to consider).
+
+ For instance, in ncurses <wchar.h> may be included if the proper
+ symbol is defined, and if ncurses is configured for wide-character
+ support. If the header is included, its symbols may be made
+ visible. That depends on the value used for _XOPEN_SOURCE feature
+ test macro.
+
+ o X/Open Curses documents one required header, in a special case:
+ <stdarg.h> before <curses.h> to prototype the vw_printw and
+ vw_scanw functions (as well as the obsolete the vwprintw and
+ vwscanw functions). Each of those uses a va_list parameter.
+
+ The two obsolete functions were introduced in SVr3. The other
+ functions were introduced in X/Open Curses. In between, SVr4
+ curses provided for the possibility that an application might
+ include either <varargs.h> or <stdarg.h>. Initially, that was done
+ by using void* for the va_list parameter. Later, a special type
+ (defined in <stdio.h>) was introduced, to allow for compiler type-
+ checking. That special type is always available, because <stdio.h>
+ is always included by <curses.h>.
+
+ None of the X/Open Curses implementations require an application to
+ include <stdarg.h> before <curses.h> because they either have
+ allowed for a special type, or (like ncurses) include <stdarg.h>
+ directly to provide a portable interface.
- Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey. Based on pcurses
+ Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey. Based on pcurses
by Pavel Curtis.
+