/************************************************************************
*                                                                       *    
*  Copyright Digital Equipment Corporation 1998. All rights reserved.   *
*                                                                       *    
*  Restricted Rights: Use, duplication, or disclosure by the U.S.       *    
*  Government is subject to restrictions as set forth in subparagraph   *    
*  (c) (1) (ii) of DFARS 252.227-7013, or in FAR 52.227-19, or in FAR   *    
*  52.227-14 Alt. III, as applicable.                                   *    
*                                                                       *    
*  This software is proprietary to and embodies the confidential        *    
*  technology of Digital Equipment Corporation. Possession, use, or     *    
*  copying of this software and media is authorized only pursuant to a  *    
*  valid written license from Digital or an authorized sublicensor.     *    
*                                                                       *    
************************************************************************/

/*      chap_2_stdio.c  */

/* This program establishes a file pointer, writes lines from   */
/* a buffer to the file, moves the file pointer to the second   */
/* record, copies the record to the buffer, and then prints     */
/* the buffer to the screen.                                    */

#include <stdio.h>
#include <stdlib.h>

main()
{
    char buffer[32];
    int i,
        pos;
    FILE *fptr;

    /*  Set file pointer.            */
    fptr = fopen("data.dat", "w+");
    if (fptr == NULL) {
        perror("fopen");
        exit(EXIT_FAILURE);
    }

    for (i = 1; i < 5; i++) {
        if (i == 2)     /*  Get position of record 2. */
            pos = ftell(fptr);
        /*  Print a line to the buffer.  */
        sprintf(buffer, "test data line %d\n", i);
        /*  Print buffer to the record.  */
        fputs(buffer, fptr);
    }

    /*  Go to record number 2.       */
    if (fseek(fptr, pos, 0) < 0) {
        perror("fseek");        /*  Exit on fseek error. */
        exit(EXIT_FAILURE);
    }

    /*  Read record 2 in the buffer. */
    if (fgets(buffer, 32, fptr) == NULL) {
        perror("fgets");        /*  Exit on fgets error.  */
        exit(EXIT_FAILURE);
    }
    /*  Print the buffer.       */
    printf("Data in record 2 is: %s", buffer);
    fclose(fptr);       /*  Close the file.     */
}