#include <iostream>
#include <string>
using namespace std;
string inp;
struct op
{
    bool type; //false is number,true is operator
    union
    {
        int number;
        char oper;
    };
} sufx[1001], prfx[1001];
int r = 0, e = 0;
int Calc()
{
    if (prfx[e].type == false)
    {
        cout<<"Calc get number!"<<prfx[e].number;
        return prfx[e].number;
    }
    else
    {
        int x, y;
        switch (prfx[e].oper)
        {
        case '+':
            ++e;
            x = Calc();
            ++e;
            y = Calc();
            return x + y;
        case '-':
            ++e;
            x = Calc();
            ++e;
            y = Calc();
            return x - y;
        case '*':
            ++e;
            x = Calc();
            ++e;
            y = Calc();
            return x * y;
        case '/':
            ++e;
            x = Calc();
            ++e;
            y = Calc();
            return x / y;
        }
    }
}
int main()
{
    cin >> inp;
    int num = 0;
    for (int i = 0; i <= inp.length(); i++)
    {
        if (inp[i] >= '0' && inp[i] <= '9')
        {
            num = num * 10 + inp[i] - '0';
        }
        else if (inp[i] == '.')
        {
            sufx[r].type = false;
            sufx[r].number = num;
            r++;
            //Save number.
            num = 0;
        }
        else if (inp[i] != '@')
        {
            sufx[r].type = true;
            sufx[r].oper = inp[i];
            ++r;
            //Save operator.
        }
    }
    //So we want to the PREFIX.
    for (int i = 0; i < r; i++)
    {
        prfx[i] = sufx[r - i - 1];
    }
    //And we can operation the end.
    int d=Calc();
    cout<<d<<endl;
    return 0;
}

我的代码运行时没有Calc函数，怎么办？