c++ - 从中缀到后缀的转换

Question

我想编写一个程序来将输入（中缀表达式）读入Queue<char>对象。输出应该是后缀表达式。在从队列到堆栈中获取值时我很困惑。

这是我的逻辑：

Stack<char> opStack;
Queue<char> postQ, infixQ;
// infixQ contains the infix expression to be converted.
// postQ contains the converted postfix expression.
char t;
while (infixQ is not empty) {
    t = infixQ.Front();
    infix.DeQueue();
    if (t is a number token) // (1)
        postQ.EnQueue(t);
    else if (opStack.IsEmpty()) // (2)
        opStack.Push(t);
    else if (t is a left paren token) // (3)
        opStack.Push(t);
    else if (t is a right paren token) { // (4)
        while (opStack.Top() is not a left paren) {
            postQ.EnQueue(opStack.Top());
            opStack.Pop();
        }
        opStack.Pop(); // discard a left paren from stack
    }
    else { // (5)
        while ( opStack is not empty and opStack.Top() != ’(’ and precedence of t <= precedence of opStack.Top()) {
            postQ.EnQueue(opStack.Top());
            opStack.Pop();
        }
        opStack.Push(t);
    }
}
// Now there are no tokens left in infixQ, so transfer remaining operators.
while (!opStack.IsEmpty()) { // (6)
    postQ.EnQueue(opStack.Top());
    opStack.Pop();
}