perror in C

Can anybody tell me the usage of perror in C language.
Please give me a simple example along with its sample run of the program.Thanks.

Man entry:
http://www.hmug.org/man/3/perror.php

--
Mats

may be this one

Code:

---

#include <errno.h>

int sock;

if( ( sock = socket( AF_INET, SOCK_STREAM, 0 ) ) == -1 )
{
    perror("socket");
    return -l;
}

---

When error occurs the global variable errno will be initialized with the error code.

ssharish