羅馬人凱撒大帝，威震歐亞非三大陸，臨終告訴侍者說:“請把我的雙手放在棺材外面，讓世人看看，偉大如我凱撒者，死後也是兩手空空。

ICounter.cs類:

interface ICounter
    {
        void Increment();
        void Decrement();
    }

Counter.cs類:

 class Counter : ICounter
    {
        private int _count = 0;
        public int Count { get { return _count; } }
        public
 
 void Increment()
        {
            _count ++;
        }

        public void Decrement()
        {
            _count--;
        }
    }

CounterLock.cs程式碼:

 class CounterLock : ICounter
    {
        private int _count;

        public int Count { get { return _count; } }
        public void
 
 Increment()
        {
            Interlocked.Increment(ref _count);
        }

        public void Decrement()
        {
            Interlocked.Decrement(ref _count);
        }
    }

Test.cs程式碼:

 class Test
    {
        public static void TestCounter(ICounter c)
        {
            for (int i = 0
 
; i < 100000; i ++)
            {
                c.Increment();
                c.Decrement();
            }
        }

        public static void RunTest()
        {
            var c1 = new Counter();
            var t1 = new Thread((() => TestCounter(c1)));
            var t2 = new Thread((() => TestCounter(c1)));
            var t3 = new Thread((() => TestCounter(c1)));
            t1.Start();
            t2.Start();
            t3.Start();
            t1.Join();
            t2.Join();
            t3.Join();

            Console.WriteLine("總數: {0}", c1.Count);
            Console.WriteLine("--------------------------");
            Console.WriteLine("普通計數器");
            Console.WriteLine("");
            var c2 = new CounterLock();
            t1 = new Thread((() => TestCounter(c2)));
            t2 = new Thread((() => TestCounter(c2)));
            t3 = new Thread((() => TestCounter(c2)));
            t1.Start();
            t2.Start();
            t3.Start();
            t1.Join();
            t2.Join();
            t3.Join();

            Console.WriteLine("總數: {0}", c2.Count);
            Console.WriteLine("--------------------------");
            Console.WriteLine("執行緒同步的計數器");

            Console.ReadKey();
        }
    }

執行結果如圖: