Outputs an error message corresponding to the error number to the standard error file (stderr).

[Format]

#include <stdio.h>

void perror (const char *s)

[Parameters]

s Pointer to error message

[Remarks]

The perror function maps errno to the error message indicated by s, and outputs the message to the standard error file (stderr).

If s is not NULL and the string pointed to by s is not a null character, the output format is as follows: the string pointed to by s followed by a colon and space, then the implementation-defined error message, and finally a new-line character.