利用栈实现简单计算器的例子(Calculator)

利用栈实现简单计算器的例子(Calculator)(1)

/* Calculator.h */
#ifndef __CALCULATOR_H__
#define __CALCULATOR_H__

#include <iostream.h>
#include "Stack.h"

class Calculator {
private:
    //存放操作数的栈
    Stack<double>   s;
    //将一个double型操作数压入栈中
    void Enter(double operand) {
        s.Push(operand);
    }
    //从栈顶读取两个操作数
    int GetTwoOperands(double &operand1, double &operand2)
    {
        if (s.StackEmpty()) {
            cerr << "No operand to pop!" << endl;
            s.ClearStack();
            return 0;
        }
        operand1 = s.Pop();
        if (s.StackEmpty()) {
            cerr << "No operand to pop!" << endl;
            s.ClearStack();
            return 0;
        }
        operand2 = s.Pop();
        return 1;
    }
    //将调用GetTwoOperands读取的两个操作数做运算op
    void Compute(char op)
    {
        double  operand1, operand2, result;
        if (!GetTwoOperands(operand1, operand2)) return;
        switch(op) {
            case '+': result = operand1 + operand2; break;