Standard library header <errno.h>

Standard library header <errno.h> - cppreference.com

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This header is part of the error handling library.

Error numbers

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