Project Akhir 1 - Tanggal

#include <stdio.h>
#include <conio.h>
#include <string.h>
#define MAKS 10

int kab (int);
int error (int, int);
void harikah (char *, char *, int);

struct date {
    int tgl, bln, thn;
    char hari[MAKS];
};

int bl, bln[] = {0,31,28,31,30,31,30,31,31,30,31,30,31};

main() {
    struct date today;
    struct date tom;
    int n, cektgl, cekbln;

    puts("=============== PROYEK AKHIR ===============\n");

    input:
    printf("Masukkan hari          : "); gets(today.hari);
    printf("Masukkan tanggal       : "); scanf("%d", &today.tgl);
    printf("Masukkan bulan         : "); scanf("%d", &today.bln);
    printf("Masukkan tahun         : "); scanf("%d", &today.thn);
    printf("Masukkan jangka hari   : "); scanf("%d", &n);

    fflush(stdin);

    // proses penyalinan value
    bl = today.bln;
    tom.tgl = today.tgl+n;
    tom.bln = today.bln;
    tom.thn = today.thn;
    strcpy(tom.hari,today.hari);

    // pengecekan kabisat
    if(kab(today.thn))
        bln[2] = 29;

    // error checking
    harikah(today.hari,tom.hari,n);
    cektgl = error(today.tgl,1);
    cekbln = error(today.bln,2);

    if(cektgl || cekbln || tom.hari[0] == '0') {
        puts("--------------------------------------------");
        printf("Data yang Anda masukkan salah, ulangi lagi\n");
        //if(
        puts("--------------------------------------------");
        goto input;
    }

    // proses penentuan tanggal
    while(tom.tgl > bln[tom.bln]) {
        tom.tgl -= bln[tom.bln];
        tom.bln += 1;
        if(tom.bln > 12) {
            tom.bln = 1;
            tom.thn += 1;
        }
    }

    // output
    puts("--------------------------------------------");
    printf("Hari ini : \nHari    : %s\n", today.hari);
    printf("Tanggal : %d\n", today.tgl);
    printf("Bulan   : %d\n", today.bln);
    printf("Tahun   : %d\n", today.thn);
    puts("--------------------------------------------");
    printf("%d Hari lagi : \nHari    : %s\n", n,tom.hari);
    printf("Tanggal : %d\n", tom.tgl);
    printf("Bulan   : %d\n", tom.bln);
    printf("Tahun   : %d\n\n", tom.thn);

    return 0;
}

int kab (int x) {
    int a;
    if(x % 400 == 0)
        a = 1;
    else if(x % 100 == 0)
        a = 0;
    else if(x % 4 == 0)
        a = 1;
    else
        a = 0;

    return (a);
}
int error (int y,int z) {
    int re;

    switch(z) {
        case 1 : if((y < 1) || (y > bln[bl])) {
                    re = 1;
                 }
        case 2 : if((y < 1) || (y > 12)) {
                    re = 1;
                 }
        default : re = 0;
    }

    return (re);
}
void harikah (char *h, char *k, int n) {
    int a, i, cek;
    char *hari[] = {"0","Senin","Selasa","Rabu","Kamis","Jumat","Sabtu","Ahad"};

    for(i=0;i<8;i++) {
        cek = strcmpi(h,hari[i]);
        if(cek == 0) {
            a = i;
            break;
        }
    }
    if(cek != 0)
        strcpy(k,hari[0]);
    else {
        a += n;
        while(a > 7) {
            a -= 7;
        }

        strcpy(k,hari[a]);
    }
}