讀入一個只包含 +, -, *, / 的非負整數計算表達式，計算該表達式的值。

#include <stdio.h>
#include <string.h>
 
#define MAX 200
 
double stack[MAX];
int tail;
 
int main()
{
 
    int a;
    while (scanf("%d ",&a) && a!=0)
    {
         tail = 0;
        //a!=0,保存在數組中
        //i 始終指向數字位置
        stack[++tail] = 1.0 * a;
        //入棧其餘剩餘的數字
        char symbol,space;
        double num;
        while (scanf("%c %lf%c",&symbol,&num,&space)!=EOF)
        {
            if (symbol == '+')
            {
                stack[++tail] = num;//1.0 * num;
            }
            else if (symbol == '-')
            {
                stack[++tail] = -1 * num;//-1.0 * num;
            }
            else if (symbol == '*')
            {
                stack[tail] = stack[tail] * num;
            }
            else if (symbol == '/')
            {
                stack[tail] = stack[tail] / num;
            }
 
            if(space != ' ')
            {
                break;
            }
             
        }
 
        //統計數組中的數值的和
        double count = 0;
        int i;
        for (i=1;i<=tail;i++)
        {
            count += stack[i];
        }
 
        printf("%.2lf\n",count);
 
 
    }
    return 1;
}