堆栈是空的...为什么？

我正在处理涉及堆栈和队列的ac＃program。队列使输入字符串入队，同时在此期间对来自队列的输入执行堆栈操作时将其出队。

现在发生的事情是在checkMatch（）中，程序给出了一个异常错误，指出堆栈为空。我已经使用了调试/调试功能，但我发现在checkMatch函数中，堆栈确实是空的，我也不明白为什么。我已经在c ++中完成了相同的程序来对其进行测试，而在c ++中我根本没有收到此错误，实际上，我得到了我想要的输出。

但是经过一整天的长时间研究，并尝试了一堆东西，包括浅拷贝，克隆等。当程序进入checkMatch函数时，我似乎仍然无法使堆栈包含某些东西。在调试活动中，我知道在checkMatch函数中堆栈和输入已重置，因此为什么我收到此堆栈为空的异常。

这是代码：

public static void loadtheInput(Queue<string> input)
{
    input.Enqueue("A"); 
    input.Enqueue("B");
    input.Enqueue("C");
    input.Enqueue("D");
}

public static void printtheLine(StreamWriter DisplayOutTxt, Queue<string> sameMatch, Stack<string> stack, Queue<string> input, string operations)
{
    string returnMatched = "";
    string returnStack = "";
    string returnInput = "";

    if (stack.Count == 0) //if stack is empty, printtheLine so DisplayOutTxt the table header
    {
        stack.Push("A"); 
        stack.Push("C");
    }
    returnMatched = printQueue(matched);
    returnStack = printStack(stack);
    returnInput = printQueue(input);
}

public static string printStack(Stack<string> stack)
{
    string DisplayOutTxt = "";
    while (stack.Count > 0) 
    {
        DisplayOutTxt += stack.Peek(); 
        stack.Pop(); 
    }
    return DisplayOutTxt;
}

private static string printQueue( Queue<string> queue)
{
    string DisplayOutTxt = "";

    if (queue.Count == 0) //if the queue is empty
    {
        DisplayOutTxt = " "; //set DisplayOutTxt to a space
    }
    else
    {
        while (queue.Count > 0) //queue not empty
        {
            DisplayOutTxt += queue.Peek(); //concat front of queue to DisplayOutTxt
            queue.Dequeue(); //dequeue the front string
        }
    }
    return DisplayOutTxt;
}

public static void checkMatch(StreamWriter DisplayOutTxt, Queue<string> sameMatch, Stack<string> stack, Queue<string> input, ref string operations)
{
    printtheLine(DisplayOutTxt, sameMatch, stack, input, operations); //print line of DisplayOutTxt

    //here is where i start facing the problem. stack (and input) are both empty once they step into this checkMatch function!
    //I think its a reference issue, but i just cant figure out what to do after everything Ive tried

    if (stack.Peek() == input.Peek()) //if the next stuff in stack and input match each other
    {
        // some code is here
    }
}

static int Main()
{
    StreamWriter DisplayOutTxt = new StreamWriter("output.txt");

    Queue<string> sameMatch = new Queue<string>();
    Stack<string> stack = new Stack<string>();
    Queue<string> input = new Queue<string>();

    string operations = "";
    loadtheInput(input); //load input into input queue and load all productions into parse table

    while (input.Count > 0) //while input vector is not empty
    {
        checkMatch(DisplayOutTxt, sameMatch, stack, input, ref operations); //call function to check for sameMatch stuff
    }
    DisplayOutTxt.Flush();
    DisplayOutTxt.Close();
    return 0;
}

继承人一些调试/步距的图像我没有以确定由被输入的checkMatch功能时的栈计数

继承人异常错误图像