Scroll to navigation

UNLOCKED_STDIO(3) Linux Programmer's Manual UNLOCKED_STDIO(3)


getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked - nonlocking stdio functions


#include <stdio.h>
int getc_unlocked(FILE *stream); int getchar_unlocked(void); int putc_unlocked(int c, FILE *stream); int putchar_unlocked(int c);
void clearerr_unlocked(FILE *stream); int feof_unlocked(FILE *stream); int ferror_unlocked(FILE *stream); int fileno_unlocked(FILE *stream); int fflush_unlocked(FILE *stream); int fgetc_unlocked(FILE *stream); int fputc_unlocked(int c, FILE *stream); size_t fread_unlocked(void *ptr, size_t size, size_t n, FILE *stream); size_t fwrite_unlocked(const void *ptr, size_t size, size_t n, FILE *stream);
char *fgets_unlocked(char *s, int n, FILE *stream); int fputs_unlocked(const char *s, FILE *stream);
#include <wchar.h>
wint_t getwc_unlocked(FILE *stream); wint_t getwchar_unlocked(void); wint_t fgetwc_unlocked(FILE *stream); wint_t fputwc_unlocked(wchar_t wc, FILE *stream); wint_t putwc_unlocked(wchar_t wc, FILE *stream); wint_t putwchar_unlocked(wchar_t wc); wchar_t *fgetws_unlocked(wchar_t *ws, int n, FILE *stream); int fputws_unlocked(const wchar_t *ws, FILE *stream);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getc_unlocked(), getchar_unlocked(), putc_unlocked(), putchar_unlocked():
clearerr_unlocked(), feof_unlocked(), ferror_unlocked(), fileno_unlocked(), fflush_unlocked(), fgetc_unlocked(), fputc_unlocked(), fread_unlocked(), fwrite_unlocked():
fgets_unlocked(), fputs_unlocked(), getwc_unlocked(), getwchar_unlocked(), fgetwc_unlocked(), fputwc_unlocked(), putwchar_unlocked(), fgetws_unlocked(), fputws_unlocked():


Each of these functions has the same behavior as its counterpart without the "_unlocked" suffix, except that they do not use locking (they do not set locks themselves, and do not test for the presence of locks set by others) and hence are thread-unsafe. See flockfile(3).


The four functions getc_unlocked(), getchar_unlocked(), putc_unlocked(), putchar_unlocked() are in POSIX.1-2001.
The nonstandard *_unlocked() variants occur on a few UNIX systems, and are available in recent glibc. They should probably not be used.


flockfile(3), stdio(3)


This page is part of release 3.74 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at