fseek() is an I/O function that is used to reposition the file indicator associated with the stream based on the values of "offset", "origin". The possible values taken by the "origin" parameter are "SEEK_SET", "SEEK_CUR", "SEEK_END". This function returns zero on success otherwise a non-zero value.

    int fseek( FILE * stream, long int offset, int origin );

   #include <stdio.h>
   int main() 
    {
      FILE * str = fopen ( "fseekeg.txt" , "w" );
      fputs ( "Its an boat." , str );
      fseek ( str , 7, SEEK_SET );
      fputs ( "coat" , str );
      fclose ( str );
      return 0;
    }

    Its an coat

In the above example the "fseek()" is used to reposition the word "boat" with coat using the offset value "7".