std::strerror - cppreference.com (original) (raw)
| | | | | ------------------------------ | | | | char* strerror( int errnum ); | | |
Returns a pointer to the textual description of the system error code errnum, identical to the description that would be printed by std::perror().
errnum is usually acquired from the errno variable, however the function accepts any value of type int. The contents of the string are locale-specific.
The returned string must not be modified by the program, but may be overwritten by a subsequent call to the strerror function. strerror is not required to be thread-safe. Implementations may be returning different pointers to static read-only string literals or may be returning the same pointer over and over, pointing at a static buffer in which strerror places the string.
[edit] Parameters
| errnum | - | integer value referring to an error code |
|---|
[edit] Return value
Pointer to a null-terminated byte string corresponding to the errno error code errnum.
[edit] Notes
POSIX allows subsequent calls to strerror to invalidate the pointer value returned by an earlier call. It also specifies that it is the LC_MESSAGES locale facet that controls the contents of these messages.
POSIX has a thread-safe version called strerror_r defined. Glibc defines an incompatible version.
[edit] Example
#include #include #include #include #include int main() { const double not_a_number = std::log(-1.0); std::cout << not_a_number << '\n'; if (errno == EDOM) { std::cout << "log(-1) failed: " << std::strerror(errno) << '\n'; std::setlocale(LC_MESSAGES, "de_DE.utf8"); std::cout << "Or, in German, " << std::strerror(errno) << '\n'; } }
Possible output:
nan log(-1) failed: Numerical argument out of domain Or, in German, Das numerische Argument ist ausserhalb des Definitionsbereiches