Ubuntu Manpage: PC, UP, BC, ospeed, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs

Provided by: ncurses-doc_6.0+20160213-1ubuntu1_all

NAME

       PC, UP, BC, ospeed, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs - direct curses
       interface to the terminfo capability database

SYNOPSIS

       #include <curses.h>
       #include <term.h>

       extern char PC;
       extern char * UP;
       extern char * BC;
       extern short ospeed;

       int tgetent(char *bp, const char *name);
       int tgetflag(char *id);
       int tgetnum(char *id);
       char *tgetstr(char *id, char **area);
       char *tgoto(const char *cap, int col, int row);
       int tputs(const char *str, int affcnt, int (*putc)(int));

DESCRIPTION

These routines are included as a conversion aid for programs that use the termcap library.
Their parameters are the same and the routines are emulated using the terminfo database.
Thus, they can only be used to query the capabilities of entries for which a terminfo
entry has been compiled.

INITIALIZATION
The tgetent routine loads the entry for name. It returns:

1 on success,

0 if there is no such entry (or that it is a generic type, having too little
information for curses applications to run), and

-1 if the terminfo database could not be found.

This differs from the termcap library in two ways:

• The emulation ignores the buffer pointer bp. The termcap library would store a
copy of the terminal description in the area referenced by this pointer. However,
ncurses stores its terminal descriptions in compiled binary form, which is not the
same thing.

• There is a difference in return codes. The termcap library does not check if the
terminal description is marked with the generic capability, or if the terminal
description has cursor-addressing.

CAPABILITY VALUES
The tgetflag routine gets the boolean entry for id, or zero if it is not available.

The tgetnum routine gets the numeric entry for id, or -1 if it is not available.

The tgetstr routine returns the string entry for id, or zero if it is not available. Use
tputs to output the returned string. The area parameter is used as follows:

• It is assumed to be the address of a pointer to a buffer managed by the calling
application.

• However, ncurses checks to ensure that area is not NULL, and also that the
resulting buffer pointer is not NULL. If either check fails, the area parameter is
ignored.

• If the checks succeed, ncurses also copies the return value to the buffer pointed
to by area, and the area value will be updated to point past the null ending this
value.

• The return value itself is an address in the terminal description which is loaded
into memory.

Only the first two characters of the id parameter of tgetflag, tgetnum and tgetstr are
compared in lookups.

FORMATTING CAPABILITIES
The tgoto routine instantiates the parameters into the given capability. The output from
this routine is to be passed to tputs.

The tputs routine is described on the terminfo(3NCURSES) manual page. It can retrieve
capabilities by either termcap or terminfo name.

GLOBAL VARIABLES
The variables PC, UP and BC are set by tgetent to the terminfo entry's data for pad_char,
cursor_up and backspace_if_not_bs, respectively. UP is not used by ncurses. PC is used
in the tdelay_output function. BC is used in the tgoto emulation. The variable ospeed is
set by ncurses in a system-specific coding to reflect the terminal speed.

RETURN VALUE

       Except where explicitly noted, routines that return an integer return ERR upon failure and
       OK (SVr4 only specifies "an integer value other than ERR") upon successful completion.

       Routines that return pointers return NULL on error.

BUGS

       If  you  call tgetstr to fetch ca or any other parameterized string, be aware that it will
       be returned in terminfo notation, not the older and not-quite-compatible termcap notation.
       This  will  not  cause  problems  if all you do with it is call tgoto or tparm, which both
       expand terminfo-style strings as terminfo.  (The tgoto function, if configured to  support
       termcap,  will check if the string is indeed terminfo-style by looking for "%p" parameters
       or "$<..>" delays, and invoke a termcap-style parser if the string does not appear  to  be
       terminfo).

       Because  terminfo  conventions for representing padding in string capabilities differ from
       termcap's, tputs("50"); will put out a  literal  "50"  rather  than  busy-waiting  for  50
       milliseconds.  Cope with it.

       Note that termcap has nothing analogous to terminfo's sgr string.  One consequence of this
       is that termcap applications assume me  (terminfo  sgr0)  does  not  reset  the  alternate
       character set.  This implementation checks for, and modifies the data shown to the termcap
       interface to accommodate termcap's limitation in this respect.

PORTABILITY