Fprintw

Fprintw is a function in the ncurses library that outputs formatted text to a FILE pointer, integrating the printf-like formatting conventions of ncurses text output. It is part of the ncurses family of print-style functions and provides a means to produce formatted output to standard file streams, not just to on-screen windows.

The function signature is int fprintw(FILE *stream, const char *fmt, ...). It formats the input according to fmt and writes the result to the specified stream. The return value is the number of characters printed, or ERR on error, following the general error convention used by ncurses. The format specifiers follow those of standard printf.

Fprintw belongs to the print family in ncurses, which also includes printw (to the stdscr window), mvprintw (move then print), wprintw (print to a WINDOW), and mvwprintw (move within a WINDOW then print). Fprintw, by contrast, redirects output to a FILE* stream rather than a curses window, making it suitable for logging, exporting text, or capturing formatted output produced by a curses-based program.

Usage considerations: like other ncurses functions, fprintw is intended for use within a curses-enabled environment; initialization of the curses library is typically required. Its behavior outside a curses session is not portable. It is commonly employed for debugging, reporting, or persisting textual data generated by a curses-driven interface.

Availability: fprintw is part of the ncurses library and is available on Unix-like systems and Windows ports that provide ncurses functionality (such as PDCurses).