errno

Go Up to errno.h Index

Header File

errno.h

Syntax

extern int errno;

Description

errno is used by perror to print error messages when certain library routines fail to accomplish their appointed tasks.

When an error in a math or system call occurs, errno is set to indicate the type of error. Sometimes errno and _doserrno are equivalent. At other times, errno does not contain the actual operating system error code, which is contained in _doserrno. Still other errors might occur that set only errno, not _doserrno.

Example

#include <errno.h>
#include <stdio.h>

int main()
{
   int i = 0;

   // Global value _sys_nerr also defined in errno.h
   while(i < _sys_nerr) {
        printf("%s\n", _sys_errlist[i]);
        i++;
   }
   return 0;
}