简单计算器

#include <stdio.h>
int main()
{
    double num, a[205];
    while(scanf("%lf", &num) != EOF)
    {
        int len = 0;
        char ch = getchar();
        char c;
        if(num == 0 && ch == ‘\n‘)
            break;
        else if(ch == ‘\n‘)
        {
            printf("%.2lf\n", num);
            continue;
        }
        a[len++] = num;
        while(scanf("%c%lf", &c, &num))
        {
            ch = getchar();
            switch(c)
            {
                case ‘+‘: a[len++] = num; break;
                case ‘-‘: a[len++] = -num; break;
                case ‘*‘: a[len-1] *= num; break;
                case ‘/‘: a[len-1] /= num;
            }
            if(ch == ‘\n‘)
                break;
        }          
        double ans = 0;
        for(int i = 0; i < len; i++)
            ans += a[i];
        printf("%.2lf\n", ans);            
    }
    return 0;
}