tgetnum

tgetnum is a function in the termcap library used to retrieve numeric terminal capability values from a terminal description loaded by tgetent. It is part of the legacy termcap interface, which predates terminfo and is still used for compatibility on many Unix-like systems.

Prototype and behavior: int tgetnum(char *id); It returns the numeric value associated with the capability named by id. If the capability is not defined for the terminal, tgetnum returns -1. The tgetent function must be successfully called prior to tgetnum; tgetent loads the terminal entry for a given terminal type into a buffer. If tgetent fails, subsequent calls to tgetnum may also fail.

Using tgetnum: After initializing with tgetent, you can request numeric capabilities such as "cols" and "lines" to determine the terminal width and height, or other numeric entries defined for the terminal description. The exact set of capabilities depends on the terminal database (termcap).

Portability and related functions: tgetnum is part of the termcap API; on modern systems, ncurses provides compatibility wrappers and the corresponding terminfo function tigetnum for terminfo databases. Code written for tgetnum can often be compiled against libtermcap, or libncurses in compatibility mode.

See also: tgetflag, tgetstr, tgetent, tigetnum, tgoto, tputs, termcap, terminfo, ncurses.