perror

From cppreference.com
< c‎ | io
Defined in header <stdio.h>
void perror( const char *s );

Prints to stderr the contents of the null-terminated character string pointed to by s (unless s is a null pointer), followed by the two characters ": ", followed by the implementation-defined error message describing the error code currently stored in the system variable errno (identical to the output of strerror(errno)), followed by '\n'.

Contents

[edit] Parameters

s - pointer to a null-terminated string with explanatory message

[edit] Return value

(none)

[edit] Example

#include <stdio.h>
 
int main(void)
{
    FILE* f = fopen("non_existent", "r");
    if (f == NULL) {
        perror("open()");
    } else {
        fclose(f);
    }
}

Output:

open(): No such file or directory

[edit] See also

returns a text version of a given error code
(function)
C++ documentation for perror