### 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>