fputc / putc / putchar / fputs / puts - glibc

Split from the chapter glibc: stdio and Formatted I/O into the per-function layout; see the method page and the glibc ledger for coverage status.

Signature – int fputc(int c, FILE *stream); int putc(int c, FILE *stream); int putchar(int c); int fputs(const char *s, FILE *stream); int puts(const char *s); plus putw(int w, FILE *stream).

Semantics – character output: fputc writes c cast to unsigned char, returning the character, or EOF on write error. putc and putchar are macro-able aliases (putc may evaluate stream twice); putchar targets stdout. Line output: fputs writes the string without the terminating NUL and without adding a newline; puts writes to stdout and appends a newline (manual, Simple Output). All set the stream error indicator and errno on failure. putw writes one int; SVID legacy, prefer fwrite.

Cancellation – fputs/puts are possible cancellation points (headers). _unlocked variants (GNU: fputs_unlocked, fputc_unlocked; POSIX: putc_unlocked, putchar_unlocked) skip the implicit lock and are the hot-path choice under flockfile.