HDU_ p1237_ Simple calculator_ stack

HDU_p1237_ Simple calculator _stack

Problem Description

Read in one containing only +, -, *, / The non negative integer evaluation expression of , Calculate the value of the expression .

Input

The test input contains several test cases , One line per test case , No more than 200 Characters , Integers and operators are separated by a space . There is no illegal expression . When there is only 0 When the input is over , Do not output the corresponding result .

Output

Output for each test case 1 That's ok , That is, the value of the expression , Accurate to the decimal point 2 position .

Sample Input

1 + 2 4 + 2 * 5 - 7 / 11 0

Sample Output

3.00 13.36

Source

Zhejiang University Computer postgraduate reexamination computer examination -2006 year

//
// #include<bits/stdc++.h>
#include<iostream>
#include<stack>
using namespace std;

int main()
{
    char ch;
    double ans,x;

    while( cin>>x )
    {
        ch=getchar();
        if( !x && ch=='\n' ) break;

        ans=0;
        stack<double> sk;
        sk.push( x );
        while( cin>>ch>>x )
        {
            switch( ch )
            {
                case '+': sk.push(x);  break;
                case '-': sk.push(-x); break;
                case '*': sk.top()*=x; break;
                case '/': sk.top()/=x; break;
            }
            if( getchar()=='\n' ) break;
        }
        while( !sk.empty() ) { ans+=sk.top(); sk.pop(); }
        printf("%.2lf\n",ans );
    }
}