ferror Function

Tests if error indicator is set.

Include

<stdio.h>

Prototype

int ferror(FILE *stream);

Argument

Return Value

Returns a non-zero value if error indicator is set; otherwise, returns a zero.

Example

/* This program tries to write to a file that is */
/* readonly. This causes the error indicator to  */
/* be set.  The function ferror is used to check */
/* the error indicator and find the error. The   */
/* function clearerr is used to reset the error  */
/* indicator so the next time ferror is called   */
/* it will not report an error.                  */

#include <stdio.h> /* for ferror, clearerr, */
                   /* printf, fprintf,      */
                   /* fopen, fclose,        */
                   /* FILE, NULL            */
int main(void)
{
  FILE *myfile;

  if ((myfile = fopen("sampclearerr.c", "r")) ==
       NULL)
    printf("Cannot open file\n");
  else
  {
    fprintf(myfile, "Write this line to the "
            "file.\n");
    if (ferror(myfile))
      printf("Error\n");
    else
      printf("No error\n");
    clearerr(myfile);
    if (ferror(myfile))
      printf("Still has Error\n");
    else
      printf("Error indicator reset\n");

    fclose(myfile);
  }
}

Example Output

Error
Error indicator reset