ATM Programing in C

‎                                          /*Note Pin code is 1234*/
#include<stdio.h>
#include<conio.h>

void main(void)
{
    unsigned long amount=2000,deposit,withdr​aw;
    int choice,pin=0,k=0;
    char another='y';

    while(pin!=1234)
    {
        clrscr();
        gotoxy(30,25);
        printf("Enter pin:");
        scanf("%d",&pin);
    }
    clrscr();
    do
    {

    printf("********Welcome to ATM Service**************\n");
    printf("1. Check Balance\n");
    printf("2. Withdraw Cash\n");
    printf("3. Deposit Cash\n");
    printf("4. Quit\n");
    printf("******************​**************************​*\n\n");
    printf("Enter your choice: ");
    scanf("%d",&choice);
    switch(choice)
    {
    case 1:
        printf("\nYour Balance is Rs : %lu ",amount);
        break;
    case 2:
        printf("\nEnter the amount to withdraw: ");
        scanf("%lu",&withdraw);
        if(withdraw%100!=0)
        {
            printf("\nPlease enter amount in multiples of 100");
        }
        else if(withdraw>(amount-500))
        {
            printf("\nInsufficient Funds");
        }
        else
        {
            amount=amount-withdraw;
            printf("\n\nPlease collect cash");
            printf("\nYour balance is %lu",amount);
        }
            break;
    case 3:
        printf("\nEnter amount to deposit");
        scanf("%lu",&deposit);
        amount=amount+deposit;
        printf("Your balance is %lu",amount);
        break;
    case 4:
        printf("\nThank you for using ATM");
        break;
    default:
        printf("\nInvalid Choice");
    }

    printf("\n\n\nDo you want another transaction?(y/n): ");
    fflush(stdin);
    scanf("%c",&another);

    if(another=='n'||another==​'N')
    k=1;
    }
    while(!k);
    printf("\n\nHave a nice day");
    getch();
}