Each of the macros defined in <errno.h> expands to an integer constant expression with type int and with a unique positive value. The following constants are defined (the implementation may define more, as long as they begin with 'E' followed by digits or uppercase letters).
| Defined in header <errno.h> | |
|---|---|
| EDOM | Mathematics argument out of domain of function (macro constant) |
| EILSEQ (C95) | Illegal byte sequence (macro constant) |
| ERANGE | Result too large (macro constant) |
Notes
Many additional errno constants are defined by POSIX and by the C++ standard library, and individual implementations may define even more, e.g. errno(3) on Linux or intro(2) on BSD and OS X.
Example
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | #include <stdio.h>#include <math.h>#include <errno.h>#include <string.h> int main(void){ errno = 0; printf("log(-1.0) = %f\n", log(-1.0)); printf("%s\n\n",strerror(errno)); errno = 0; printf("log(0.0) = %f\n", log(0.0)); printf("%s\n",strerror(errno));} |
Possible output:
1 2 3 4 5 | log(-1.0) = nanNumerical argument out of domain log(0.0) = -infNumerical result out of range |
References
- C11 standard (ISO/IEC 9899:2011):
- 7.5/2 Errors <errno.h> (p: 205)
- C99 standard (ISO/IEC 9899:1999):
- 7.5/2 Errors <errno.h> (p: 186)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.1.3 Errors <errno.h>
See also
| macro which expands to POSIX-compatible thread-local error number variable (macro variable) | |
displays a character string corresponding of the current error to stderr (function) | |
| (C11)(C11) | returns a text version of a given error code (function) |
C++ documentation for Error numbers | |
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