#include <iostream>#include <stack>#include <sstream>#include <string>#include <iomanip>using namespace std ;stack<double> num ;stack<char> oper ;void compute(char op){double a = num.top() ;num.pop() ;double b = num.top() ;num.pop() ;switch(op){case '-' : num.push(b-a) ; break ;case '+' : num.push(b+a) ; break ;case '*' : num.push(b*a) ; break ;case '/' : num.push(b/a) ; break ;default : break ;}}int main(){string s ;while(getline(cin,s) && s != string("0")){s.push_back(' ') ;s.push_back('=') ;stringstream st(s) ;int n ;char op ;while(st>>n>>op){num.push(n) ;if(op == '+' || op == '-'){while(!oper.empty()){char c = oper.top() ;oper.pop() ;compute(c) ;}oper.push(op) ;}else if(op == '*' || op == '/' ){while(!oper.empty() && (oper.top() == '*' || oper.top() == '/' )){char c = oper.top() ;oper.pop() ;compute(c) ;}oper.push(op) ;}else if(op == '='){while(!oper.empty()){char c = oper.top() ;compute(c) ;oper.pop() ;}cout << fixed << setprecision(2);cout << num.top() << endl;num.pop() ;break ;}}}return 0 ;}与君共勉
，生气是拿别人做错的事来惩罚自己
