Polish calculation

//cww 逆波兰计算器
#include<stack>
#include<cstdio>
#include<iostream>
using namespace std;
stack<double>s;

char read(){
    while (1){
        printf("Select command and press<Enter>:");
        char ch; cin>>ch;
        if (ch=='?'||ch=='='||ch=='+'||
            ch=='-'||ch=='*'||ch=='/'||
            ch=='q'||ch=='Q')return ch;
        puts("Please enter a valid command:");
        puts("[?]push to stack [=]print top");
        puts("[+] [-] [*] [/] you know them");
        puts("[Q]uit =======Bazinga!=======");
    }
}

bool solve(char ch){
    double x,y;
    if (ch=='q'||ch=='Q'){
        puts("Calculation finshed.");
        return 0;
    }
    if (ch=='?'){
        printf("Enter a real number:");
        cin>>x; s.push(x);
    }
    if (ch=='='){
        if (s.empty())puts("Stack empty");
        else printf("%.0lf
",s.top());
    }
    if (ch=='+'||ch=='-'||ch=='*'||ch=='/'){
        if (s.empty())puts("Stack empty");
        else{
            x=s.top(); s.pop();
            if (s.empty()){
                puts("Stack has just one entry");
                s.push(x);
            }
            else{
                y=s.top();s.pop();
                switch (ch){
                    case'+':s.push(x+y);break;
                    case'-':s.push(x-y);break;
                    case'*':s.push(x*y);break;
                    case'/':s.push(x/y);break;
                }
            }
        }
    }
    return 1;
}
//==========cww=2016,2,28=23:27=============== 
int main(){
    puts("welcome");
    while (!s.empty())s.pop();
    while (solve(read())){}
    return 0;
}