errono should always be checked after calling any function in which it might be set.
errono should always be checked after calling any function in which it might be set.
# include <errno> // include errno definition ... double x = ...; errno = 0; // clear out error flag double d = sqrt(x); if (errno == EDOM) // test global status flag ... // handle error case
// is sqrt evaluated first, or g? double d = sqrt(x) * g(); // worse, what happens if g clears // a flag that was set by sqrt ? double g () { errno = 0; return 3.14159 * sin(42); }