C library function - clearerr()

Description

The C library function void clearerr(FILE *stream) clears the end-of-file and error indicators for the given stream.

Declaration

Following is the declaration for clearerr() function.

void clearerr(FILE *stream)

Parameters

• stream -- This is the pointer to a FILE object that identifies the stream.

Return Value

This should not fail and do not set the external variable errno but in case it detects that its argument is not a valid stream, it must return -1 and set errno to EBADF.

Example

The following example shows the usage of clearerr() function.

#include <stdio.h>

int main()
{
   FILE *fp;
   char c;

   fp = fopen("file.txt", "w");

   c = fgetc(fp);
   if( ferror(fp) )
   {
      printf("Error in reading from file : file.txt\n");
   }
   clearerr(fp);
   if( ferror(fp) )
   {
      printf("Error in reading from file : file.txt\n");
   }
   fclose(fp);

   return(0);
}

Assuming we have a text file file.txt, which is an empty file. Let us compile and run the above program, this will produce the following result because we try to read a file which we opened in write only mode.

Error reading from file "file.txt"