perror -- Print Error Message

Format

#include <stdio.h>
void perror(const char *string);

Language Level: ANSI, POSIX, XPG4
perror prints an error message to stderr. If string is not NULL and does not point to a null character, the string pointed to by string is printed to the standard error stream, followed by a colon and a space. The message associated with the value in errno is then printed followed by a new-line character.

To produce accurate results, you should ensure that perror is called immediately after a library function returns with an error; otherwise, subsequent calls may alter the errno value.

Return Value
There is no return value.

Example
This example tries to open a stream. If fopen fails, the example prints a message and ends the program.

#include <stdio.h>
#include <stdlib.h>
#define FILENAME "myfile.mjq"
int main(void)
{
   FILE *fh;
   if ((fh = fopen(FILENAME,"r")) == NULL)
   {
      perror("Could not open data file");
      abort();
   }
   return 0;
   /*******************************************************
      The output should be:
      Could not open data file: The file cannot be found.
   *******************************************************/
}


clearerr -- Reset Error Indicators
ferror -- Test for Read/Write Errors
strerror -- Set Pointer to Runtime Error Message
_strerror -- Set Pointer to System Error String
<stdio.h>