// using System.Threading;
class Account
{ private Object thisLock = new Object();
int balance;
Random r = new Random();
public Account(int initial)
{
balance = initial;
} int Withdraw(int amount)
{ // This condition never is true unless the lock statement
// is commented out.
if (balance < 0)
{
throw new Exception("Negative Balance");
} // Comment out the next line to see the effect of leaving out
// the lock keyword.
lock (thisLock)
{
if (balance >= amount)
{
Console.WriteLine("Balance before Withdrawal : " + balance);
Console.WriteLine("Amount to Withdraw : -" + amount);
balance = balance - amount;
Console.WriteLine("Balance after Withdrawal : " + balance);
return amount;
}
else
{
return 0; // transaction rejected
}
}
} public void DoTransactions()
{
for (int i = 0; i < 100; i++)
{
Withdraw(r.Next(1, 100));
}
} }
class Test
{
static void Main()
{ Thread[] threads = new Thread[10];
Account acc = new Account(1000);
for (int i = 0; i < 10; i++)
{
Thread t = new Thread(new ThreadStart(acc.DoTransactions));
threads[i] = t;
}
for (int i = 0; i < 10; i++)
{
threads[i].Start();
}
}
}