printw, wprintw, mvprintw, mvwprintw, vwprintw, vw_printw - print formatted output in curses windows
int printw(const char *fmt, ...);
int wprintw(WINDOW *win, const char *fmt, ...);
int mvprintw(int y, int x, const char *fmt, ...);
int mvwprintw(WINDOW *win, int y, int x, const char *fmt, ...);
int vw_printw(WINDOW *win, const char *fmt, va_list varglist);
/* obsolete */
int vwprintw(WINDOW *win, const char *fmt, va_list varglist);
The printw, wprintw, mvprintw and mvwprintw routines are analogous to printf [see printf(3)]. In effect, the string that would be output by printf is output instead as though waddstr were used on the given window.
The vwprintw and vw_printw routines are analogous to vprintf [see printf(3)] and perform a wprintw using a variable argument list. The third argument is a va_list, a pointer to a list of arguments, as defined in <stdarg.h>.
Routines that return an integer return ERR upon failure and OK (SVr4 only specifies "an integer value other than ERR") upon successful completion.
X/Open defines no error conditions. In this implementation, an error may be returned if it cannot allocate enough memory for the buffer used to format the results. It will return an error if the window pointer is null.
Functions with a “mv” prefix first perform a cursor movement using wmove, and return an error if the position is outside the window, or if the window pointer is null.
While printw was implemented in 4BSD, it was unused until 4.2BSD (which used it in games). That early version of curses was before the ANSI C standard. It did not use <varargs.h>, though that was available. In 1991 (a couple of years after SVr4 was generally available, and after the C standard was published), other developers updated the library, using <stdarg.h> internally in 4.4BSD curses. Even with this improvement, BSD curses did not use function prototypes (or even declare functions) in the <curses.h> header until 1992.
SVr2 documented printw, wprintw tersely as “printf on stdscr” and tersely as “printf on win”, respectively.
SVr3 added mvprintw, and mvwprintw, with a three-line summary saying that they were analogous to printf(3), explaining that the string which would be output from printf(3) would instead be output using waddstr on the given window. SVr3 also added vwprintw, saying that the third parameter is a va_list, defined in <varargs.h>, and referring the reader to the manual pages for varargs and vprintf for detailed descriptions.
SVr4 added no new variations of printw, but provided for using <varargs.h> or <stdarg.h> to define the va_list type.
X/Open Curses added vw_printw to replace vwprintw, stating that its va_list definition requires <stdarg.h>.
In this implementation, vw_printw and vwprintw are equivalent, to support legacy applications. However, the latter (vwprintw) is obsolete:
- The XSI Curses standard, Issue 4 described these functions. The function vwprintw is marked TO BE WITHDRAWN, and is to be replaced by a function vw_printw using the <stdarg.h> interface.
- The Single Unix Specification, Version 2 states that vw_printw is preferred to vwprintw since the latter requires including <varargs.h>, which cannot be used in the same file as <stdarg.h>. This implementation uses <stdarg.h> for both, because that header is included in <curses.h>.
- X/Open Curses, Issue 5 (December 2007) marked vwprintw (along with vwscanw and the termcap interface) as withdrawn.