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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | ATTRIBUTES | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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unlocked_stdio(3) Library Functions Manual unlocked_stdio(3)
getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked -
nonlocking stdio functions
Standard C library (libc, -lc)
#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 *_Nullable stream);
int fgetc_unlocked(FILE *stream);
int fputc_unlocked(int c, FILE *stream);
size_t fread_unlocked(size_t size, size_t n;
void ptr[restrict size * n],
size_t size, size_t n,
FILE *restrict stream);
size_t fwrite_unlocked(size_t size, size_t n;
const void ptr[restrict size * n],
size_t size, size_t n,
FILE *restrict stream);
char *fgets_unlocked(int n;
char s[restrict n], int n, FILE *restrict stream);
int fputs_unlocked(const char *restrict s, FILE *restrict 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(int n;
wchar_t ws[restrict n], int n,
FILE *restrict stream);
int fputws_unlocked(const wchar_t *restrict ws,
FILE *restrict stream);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
getc_unlocked(), getchar_unlocked(), putc_unlocked(),
putchar_unlocked():
/* glibc >= 2.24: */ _POSIX_C_SOURCE >= 199309L
|| /* glibc <= 2.23: */ _POSIX_C_SOURCE
|| /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
clearerr_unlocked(), feof_unlocked(), ferror_unlocked(),
fileno_unlocked(), fflush_unlocked(), fgetc_unlocked(),
fputc_unlocked(), fread_unlocked(), fwrite_unlocked():
/* glibc >= 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
fgets_unlocked(), fputs_unlocked(), getwc_unlocked(),
getwchar_unlocked(), fgetwc_unlocked(), fputwc_unlocked(),
putwchar_unlocked(), fgetws_unlocked(), fputws_unlocked():
_GNU_SOURCE
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).
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────┬───────────────┬─────────────────────────┐
│ Interface │ Attribute │ Value │
├──────────────────────┼───────────────┼─────────────────────────┤
│ getc_unlocked(), │ Thread safety │ MT-Safe race:stream │
│ putc_unlocked(), │ │ │
│ clearerr_unlocked(), │ │ │
│ fflush_unlocked(), │ │ │
│ fgetc_unlocked(), │ │ │
│ fputc_unlocked(), │ │ │
│ fread_unlocked(), │ │ │
│ fwrite_unlocked(), │ │ │
│ fgets_unlocked(), │ │ │
│ fputs_unlocked(), │ │ │
│ getwc_unlocked(), │ │ │
│ fgetwc_unlocked(), │ │ │
│ fputwc_unlocked(), │ │ │
│ putwc_unlocked(), │ │ │
│ fgetws_unlocked(), │ │ │
│ fputws_unlocked() │ │ │
├──────────────────────┼───────────────┼─────────────────────────┤
│ getchar_unlocked(), │ Thread safety │ MT-Unsafe race:stdin │
│ getwchar_unlocked() │ │ │
├──────────────────────┼───────────────┼─────────────────────────┤
│ putchar_unlocked(), │ Thread safety │ MT-Unsafe race:stdout │
│ putwchar_unlocked() │ │ │
├──────────────────────┼───────────────┼─────────────────────────┤
│ feof_unlocked(), │ Thread safety │ MT-Safe │
│ ferror_unlocked(), │ │ │
│ fileno_unlocked() │ │ │
└──────────────────────┴───────────────┴─────────────────────────┘
getc_unlocked()
getchar_unlocked()
putc_unlocked()
putchar_unlocked()
POSIX.1-2008.
Others:
None.
getc_unlocked()
getchar_unlocked()
putc_unlocked()
putchar_unlocked()
POSIX.1-2001.
flockfile(3), stdio(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-06-28 unlocked_stdio(3)
Pages that refer to this page: ferror(3), fflush(3), fgetc(3), fgetwc(3), fgetws(3), fileno(3), flockfile(3), fputwc(3), fputws(3), fread(3), gets(3), getwchar(3), puts(3), putwchar(3), stdio(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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