Polish calculation

Posted by Cww97 on 2016-03-14

版权声明:本文为博主原创文章,未经博主允许不得转载。原文所在http://blog.csdn.net/cww97 https://blog.csdn.net/cww97/article/details/50887830

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//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\n",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;
}