/*
 * Author  : Amit Dutta <amitdutta4255@gmail.com>
 * Date    : 08 Feb 2026
 * Repo    : https://github.com/notamitgamer/bsc
 * License : MIT License (See the LICENSE file for details)
 */

/* Store date in a structure using bit fields (day: 5 bits, month: 4 bits, year: 12 bits). Read joining dates of 10 employees and display them sorted by year.
*/
/* Let Us C, Chap- 22 (Miscellaneous Features), Qn No.: C(a) */

/* This file is auto-generated by a bot. */
/* This code is not compiled; it is for reference only. */


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

// Define structure with bit-fields
struct date
{
    unsigned int day : 5;   // 1-31 takes 5 bits
    unsigned int month : 4; // 1-12 takes 4 bits
    unsigned int year : 12; // Sufficient for year 0-4095
};

struct employee
{
    char name[30];
    struct date doj; // Date of Joining
};

int compare_dates(const void *a, const void *b);

int main()
{
    struct employee emp[10];
    int i;
    // Temporary variables for input because we cannot take address of a bit-field
    int d, m, y; 

    printf("Enter details for 10 employees:\n");
    for (i = 0; i < 10; i++)
    {
        printf("\nEmployee %d Name: ", i + 1);
        scanf("%s", emp[i].name);

        printf("Date of Joining (dd mm yyyy): ");
        scanf("%d %d %d", &d, &m, &y);

        // Assign to bit-fields
        emp[i].doj.day = d;
        emp[i].doj.month = m;
        emp[i].doj.year = y;
    }

    // Sort based on year using qsort
    qsort(emp, 10, sizeof(struct employee), compare_dates);

    printf("\n--- Employees Sorted by Joining Year ---\n");
    for (i = 0; i < 10; i++)
    {
        printf("%-15s | DOJ: %02d-%02d-%d\n", 
               emp[i].name, emp[i].doj.day, emp[i].doj.month, emp[i].doj.year);
    }

    return 0;
}

int compare_dates(const void *a, const void *b)
{
    struct employee *e1 = (struct employee *)a;
    struct employee *e2 = (struct employee *)b;

    // Primary sort by Year
    if (e1->doj.year != e2->doj.year)
        return e1->doj.year - e2->doj.year;
    
    // Secondary sort by Month
    if (e1->doj.month != e2->doj.month)
        return e1->doj.month - e2->doj.month;
        
    // Tertiary sort by Day
    return e1->doj.day - e2->doj.day;
}