Question

Write a C program to simulate deposit/withdraw activities on a banking account. (Hint: you might want to review Lab 3 slides.) (25 points)

 Declare the balance as a global variable and initialize it to 600.  Write two functions, one for withdraw, the other for deposit. Both withdraw and deposit functions have one parameter, which represent the amount to withdraw or deposit. The functions deduct the balance and add to the balance one dollar at a time, respectively. Therefore, to withdraw 600 thousands, for example, the withdraw function has to execute a loop with 600 thousand iterations. The deposit function works in the same way, in the reverse direction.  Create two Posix threads in main(), which call the withdraw and the deposit function respectively.  Use pthread_mutex_lock() and pthread_mutex_unlock() functions to ensure mutual exclusion between the two threads. Also make sure to use pthread_join() to wait for the threads to terminate.

Answer 1

CODE:

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

int balance=600;
pthread_mutex_t lock;
void *withdraw(void *amt)
{
   pthread_mutex_lock(&lock);
   int i;
   int *amount;
   amount = (int *) amt;
   if(*amount > balance)
   {
       printf("Insufficient balance to withdraw\n");
       return NULL;
   }
   for(i = 0; i < *amount; i++)
       balance -=1;

   pthread_mutex_unlock(&lock);

}

void *deposit(void *amt)
{
   pthread_mutex_lock(&lock);
   int i;
   int *amount;
   amount = (int *) amt;
   for(i = 0; i < *amount; i++)
       balance +=1;

   pthread_mutex_unlock(&lock);
}
int main()
{
   pthread_t dep, withd;
   int amount,choice;
   char ch = 'y';

   do
   {
       printf("\nChoose Option :\n");
       printf("1. Deposit\n2. Withdraw\n");
       scanf("%d",&choice);

       switch(choice)
       {
           case 1:
               printf("Enter amount to deposit : ");
               scanf("%d", &amount);

               pthread_create(&dep, NULL, deposit, (void*) &amount);   //create thread for deposit
               pthread_join(dep, NULL);
               printf("Balance : %d\n", balance);
               break;
        
           case 2:
               printf("Enter amount to withdraw : ");
               scanf("%d", &amount);

               pthread_create(&withd, NULL, withdraw, (void*) &amount); //create thread for withdrawal
               pthread_join(withd, NULL);
               printf("Balance : %d\n", balance);
               break;
        
           default:
               printf("\n Invalid choice\n");
               break;

       }
       printf("\nDo you want to continue[y/n] : ");
       scanf(" %c",&ch);
   }while(ch == 'y');
   return 0;

}