Создание программы, которая будет следить за посещаемостью - C (СИ)

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
 
#define START_TIME ( 1417158000 )
#define WORK_TIME ( 8 * 60 * 60 )
#define DELAY_TIME ( 15 * 60 )
 
enum WORKER_STATE { WS_OUT, WS_IN };
#define MAX_STR_LENGTH ( 32 )
 
typedef struct WORKER {
    int cardID;
    char name[MAX_STR_LENGTH];
} worker_t;
 
 
#define NUM_WORKERS ( 3 )
 
typedef struct RECORD {
    time_t timeStamp;
    int cardID;
    int state;
} record_t;
 
typedef struct REPORT {
    const worker_t * pWorker;
    time_t timeIn;
    time_t timeOut;
} report_t;
 
int create_report(report_t * pRep, const worker_t * pWorker, const record_t * pRecords, const size_t recordsCount) {
    size_t i;
    
    pRep->pWorker = pWorker;
    for ( i = 0; i < recordsCount; ++i ) {
        if ( pWorker->cardID == pRecords[i].cardID ) {
            switch ( pRecords[i].state ) {
                case WS_OUT :
                    pRep->timeOut = pRecords[i].timeStamp;
                    break;
                case WS_IN :
                    pRep->timeIn = pRecords[i].timeStamp;
                    break;
                default :
                    return -1;
            }
        }
    }
    
    return 0;
}
 
#define SEPARATOR_LINE "+---------+----------------------+------------+------------+------------+"
#define HEADER         "| card ID | Worker name          | Incoming   | Outgoing   | On place   |"
 
void print_report(const report_t * pRep) {
    char inStr[MAX_STR_LENGTH], outStr[MAX_STR_LENGTH], onplaceStr[MAX_STR_LENGTH];
    long onPlace;
    
    strftime(inStr, MAX_STR_LENGTH, "%H:%M", localtime(&(pRep->timeIn)));
    strftime(outStr, MAX_STR_LENGTH, "%H:%M", localtime(&(pRep->timeOut)));
    onPlace = (long)(pRep->timeOut - pRep->timeIn);
    sprintf(onplaceStr, "%u:%02u", onPlace / 60 / 60, onPlace / 60 % 60);
    
    printf("| %-7d | %-20s | %-10s | %-10s | %-10s |\n", pRep->pWorker->cardID, pRep->pWorker->name, inStr, outStr, onplaceStr);
}
 
int shuffle(const void * a, const void * b) {
    return rand() - rand();
}
 
int reports_by_name(const void * a, const void * b) {
    return strcmp(((report_t*)a)->pWorker->name, ((report_t*)b)->pWorker->name);
}
 
int reports_by_incoming(const void * a, const void * b) {
    return (int)(((report_t*)a)->timeIn - ((report_t*)b)->timeIn);
}
 
int reports_by_outgoing(const void * a, const void * b) {
    return (int)(((report_t*)a)->timeOut - ((report_t*)b)->timeOut);
}
 
int reports_by_onplace(const void * a, const void * b) {
    report_t * pA = (report_t*)a;
    report_t * pB = (report_t*)b;
    
    return (int)((pA->timeOut - pA->timeIn) - (pB->timeOut - pB->timeIn));
}
 
int main(void) {
    worker_t workers[NUM_WORKERS] = {
        { 1, "Ivanov" },
        { 2, "Petrov" },
        { 3, "Sidorov" }
    };
    report_t reports[NUM_WORKERS];
    record_t records[NUM_WORKERS * 2];
    int i, rec = 0;
    time_t currentTime = START_TIME;
    
    srand(time(NULL));
    
    /* Пришли на работу */
    qsort(workers, NUM_WORKERS, sizeof(worker_t), shuffle);
    for ( i = 0; i < NUM_WORKERS; ++i ) {
        currentTime += rand() % DELAY_TIME;
        records[rec].cardID = workers[i].cardID;
        records[rec].timeStamp = currentTime;
        records[rec].state = WS_IN;
        ++rec;
    }
    
    /* Ушли с работы */
    currentTime = START_TIME + WORK_TIME;
    qsort(workers, NUM_WORKERS, sizeof(worker_t), shuffle);
    for ( i = 0; i < NUM_WORKERS; ++i ) {
        currentTime += rand() % DELAY_TIME;
        records[rec].cardID = workers[i].cardID;
        records[rec].timeStamp = currentTime;
        records[rec].state = WS_OUT;
        ++rec;
    }
    
    /* Составили отчёт */
    for ( i = 0; i < NUM_WORKERS; ++i )
        if ( create_report(&reports[i], &workers[i], records, rec) )
            return 1;
    
    qsort(reports, NUM_WORKERS, sizeof(report_t), reports_by_name);
    printf("Sorted by name:\n");
    printf("%s\n%s\n%s\n", SEPARATOR_LINE, HEADER, SEPARATOR_LINE);
    for ( i = 0; i < NUM_WORKERS; ++i ) {
        print_report(&reports[i]);
        printf("%s\n", SEPARATOR_LINE);
    }
    
    printf("Press ENTER...");
    getchar();
    
    qsort(reports, NUM_WORKERS, sizeof(report_t), reports_by_incoming);
    printf("Sorted by incoming:\n");
    printf("%s\n%s\n%s\n", SEPARATOR_LINE, HEADER, SEPARATOR_LINE);
    for ( i = 0; i < NUM_WORKERS; ++i ) {
        print_report(&reports[i]);
        printf("%s\n", SEPARATOR_LINE);
    }
    
    printf("Press ENTER...");
    getchar();
    
    qsort(reports, NUM_WORKERS, sizeof(report_t), reports_by_outgoing);
    printf("Sorted by outgoing:\n");
    printf("%s\n%s\n%s\n", SEPARATOR_LINE, HEADER, SEPARATOR_LINE);
    for ( i = 0; i < NUM_WORKERS; ++i ) {
        print_report(&reports[i]);
        printf("%s\n", SEPARATOR_LINE);
    }
    
    printf("Press ENTER...");
    getchar();
    
    qsort(reports, NUM_WORKERS, sizeof(report_t), reports_by_onplace);
    printf("Sorted by onplace:\n");
    printf("%s\n%s\n%s\n", SEPARATOR_LINE, HEADER, SEPARATOR_LINE);
    for ( i = 0; i < NUM_WORKERS; ++i ) {
        print_report(&reports[i]);
        printf("%s\n", SEPARATOR_LINE);
    }
    
    printf("Press ENTER...");
    getchar();
    
    return 0;
}