7.21.6.2 The strerror function
Synopsis
#include <string.h>
char *strerror(int errnum);
Description
The strerror function maps the number in errnum to a message string. Typically, the values for errnum come from errno, but strerror shall map any value of type int to a message.
The implementation shall behave as if no library function calls the strerror function.
Returns
The strerror function returns a pointer to the string, the contents of which are locale- specific. The array pointed to shall not be modified by the program, but may be overwritten by a subsequent call to the strerror function.