SAS/C Library Reference, Vol. 1

rewind -- Position to Start of File

SYNOPSIS

 #include <stdio.h>

 void rewind(FILE *f);

DESCRIPTION

rewind positions the stream associated with the FILE object addressed by f to its first character. It also resets the error flag for the stream if it is set.

RETURN VALUE

rewind has no return value.

EXAMPLE

This example searches for the nth record in a file, returns that record, and rewinds the file after the search is finished:

  #include <stdio.h>
  #define RECLEN 80

  FILE *f;           /* file to be searched                 */
  char *search(int); /* prototype of the search function    */

  main()
  {
     int n ;         /* The record number to be found       */
                     /*  points to the address of a copy of */
                     /*  the returned record.               */
     char *addr;

        /* Ask the user for the number of the record to     */
        /*  be found.                                       */
     puts("Which record do you want to read?");
     scanf("%d", &n);
     addr = search(n);
     printf("The record is %sn", *addr);
  }
     /* performs the search and rewind of the file f        */
  char *search(int n){
     char *record;   /* points to a copy of the record      */
     int i;
     while (!feof(f)) {

           /* Read the records until the nth one is found.  */
        for (i=0; i <= n; i++)
           afread(record, RECLEN, 1, f);
     }

        /* Reposition the stream to the top of f.           */
     rewind(f);

        /* Return the address of the copy of the record.    */
     return record;
  }

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