Figure 1:


#define HEADER_LENGTH 256      /* Length of header record */
#define DELETE_FLAG 0xFF       /* Record delete flag */
#define RECORD_SIZE 11         /* Size of record */
#define READ_ONLY_BINARY "rb"  /* Compiler dependent read binary mode */

/* The record has two fields:
    Number (5 characters)
    Name   (6 characters)
*/

#include "STDIO.H"

int main(argc, argv)
/* Reads fixed length database file */
/* The file is specified on the command line */
/* e.g. readdata filename */
int argc;
char *argv[];
    {
    FILE *file;             /* Input file */
    int ret;                /* Return from functions */
    char buffer[100];       /* Input buffer */
    int number;             /* Data item in record */
    static char name[7];    /* Data item in record */ 
    int record_number;      /* Current record number */

    record_number = 0;

    if (argc > 1)
        {
        file = fopen(argv[1], READ_ONLY_BINARY);
        if (file != NULL)
            {
            ret = fseek(file, (long) HEADER_LENGTH, 0);
            if (ret == 0)
                {
                /* Begin reading records. Break when read returns 
                    less than record size */
                while (1)
                    {
                    ret = fread(buffer, 1, RECORD_SIZE, file);
                    if (ret < RECORD_SIZE)
                        {
                        printf("\n End of file");
                        break;
                        }
                    else 
                        {
                        record_number++;
                        /* Check the delete flag */
                        if (buffer[0] == DELETE_FLAG)
                            {
                            printf("\n Deleted record %d", record_number);
                            }
                        else 
                            {
                            /* Decode the record */
                            ret = sscanf(buffer, "%5d%6s", &number, name);
                            if (ret != 2)
                                {
                                printf("\n Error in record decoding %d ret %d",
                                    record_number, ret);
                                }
                            else 
                                {
                                /* Print decoded record */
                                printf("\n Record %d is %d %6s",
                                    record_number, number, name);
                                }
                            }
                        }
                    }
                }        /* End of successful header read */
            else 
                {
                printf("\n Unable to read header record");
                }
            }            /* End of successful open */
        else 
            {
            printf("\n Unable to open file %s", argv[1]);
            }
        }                /* End of successful argument count */
    else 
        {
        printf("\n Usage is readdata filename");
        }
    exit(0);
    }