Standard library header <errno.h>

 

C

Compiler support

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Strings library

Algorithms

Numerics

Date and time utilities

Input/output support

Localization support

Concurrency support (C11)

Technical Specifications

Symbol index

 

Standard Library headers

<assert.h> <complex.h> (C99) <ctype.h> <errno.h> <fenv.h> (C99) <float.h> <inttypes.h> (C99)     <iso646.h> (C95) <limits.h> <locale.h> <math.h>

<setjmp.h> <signal.h> <stdalign.h> (C11*) <stdarg.h> <stdatomic.h> (C11)     <stdbit.h> (C23) <stdbool.h> (C99*) <stdckdint.h> (C23) <stddef.h> <stdint.h> (C99) <stdio.h>

<stdlib.h> <stdmchar.h> (C29) <stdnoreturn.h> (C11*) <string.h> <tgmath.h> (C99) <threads.h> (C11) <time.h> <uchar.h> (C11) <wchar.h> (C95) <wctype.h> (C95)

 

This header is part of the error handling library.

Error numbers

errno	macro which expands to POSIX-compatible thread-local error number variable (macro variable)
E2BIG, EACCES, ..., EXDEV	macros for standard POSIX-compatible error conditions (macro constant)

Synopsis

#define EDOM   /* implementation-defined */
#define EILSEQ /* implementation-defined */
#define ERANGE /* implementation-defined */

#define errno  /* implementation-defined */

// Only if the implementation defines __STDC_LIB_EXT1__ and additionally the user code
// defines __STDC_WANT_LIB_EXT1__ before any inclusion of <errno.h>:
#ifdef __STDC_WANT_LIB_EXT1__
#define __STDC_LIB_EXT1__  /* implementation-defined */
#define errno_t            /* implementation-defined */
#endif