calculator.cpp

中缀表达式转中缀表达式

#include"mystack.h"
#include"CalculatorH.h"
#include<iostream.h>
#include<assert.h>

void Calculator::AddOperand(double value){
	s.push(value);
}

Boolean Calculator::Get2Operand(double &left,double &right){
	assert(!s.isEmptyStack());
	right = s.pop();
	assert(!s.isEmptyStack());
	left = s.pop();
	return True;
}

void Calculator::DoOperator(char op){
	double left,right;
	if (Get2Operand(left,right)==True){
		switch(op){
		case'+':s.push(left + right);break;
		case'-':s.push(left - right);break;
		case'*':s.push(left * right);break;
		case'/':assert(right);s.push(left / right);break;
		}
	}
	else s.clear();
}

void Calculator::Run(){
	char ch;
	cout<<"Please input a postfix expression:\n";
	while(cin.get(ch),ch!='='){
		switch(ch){
		case'(':case'+':case'-':case'*':case'/':
			DoOperator(ch);break;
		case' ':break;
		default:
			cin.putback(ch);
			double newoperand;cin>>newoperand;
			AddOperand(newoperand);
			break;
		}
	}
	cout<<s.top()<<endl;
}