Error numbers

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 by ISO C. The implementation may define more, as long as they begin with 'E' followed by digits or uppercase letters.

[edit] 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.

[edit] Example

#include <errno.h>
#include <math.h>
#include <stdio.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));
}

log(-1.0) = nan
Numerical argument out of domain
 
log(0.0) = -inf
Numerical result out of range

[edit] References

[edit] See also

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