声明：这是老师的代码

不愧是老师的代码

#include <bits/stdc++.h>
using namespace std;
double nibolan(){
	char c[20];
	cin >> c;
	switch (c[0]){
		case '+':
			return nibolan() + nibolan();
		case '-':
			return nibolan() - nibolan();
		case '*':
			return nibolan() * nibolan();
		case '/':
			return nibolan() / nibolan();
		default:
			return atof(c);
			break;
	}
}
int main(int argc, char **argv){
	printf("%f",nibolan());
	return 0;
}

分享一下写了两小时的⑩

#include<iostream>
#include<iomanip>
#include<string>
#include<stack>
#include<cstdio>
#include<math.h>
using namespace std;
string a[114];
stack<double> s;
double sum;
int len=1;
double t3,t4;
char t;
void prepare(char n,double a,double b,double &sum){
	if(n=='+') sum=a+b;
	else if(n=='-') sum=a-b;
	else if(n=='*') sum=a*b;
	else if(n=='/') sum=a/b;
}
int main() {
	while(cin>>a[len]) len++;
	cout<<endl<<endl;
	for(; len>0; len--) {
		if(a[len]=="+"||a[len]=="-"||a[len]=="*"||a[len]=="/") {
			t3=s.top();
			s.pop();
			t4=s.top();
			s.pop();
			t=a[len][0];
			prepare(t,t3,t4,sum);
			s.push(sum);
		} else {
			sum=atof(a[len].c_str());
			s.push(sum);
		}
	}
	printf ("%f",s.top());
	return 0;
}

是栈我们没救了

#include <bits/stdc++.h>
using namespace std;
double fufuhang(){
	char c[20];
	cin>>c;
	switch(c[0]){
		case '+': return fufuhang() + fufuhang();
		case '-': return fufuhang() - fufuhang();
		case '*': return fufuhang() * fufuhang();
		case '/': return fufuhang() / fufuhang();
		default:
			return atof(c);
			break;
	}
}//大名为武则天计算器！ 
int main(){
	cout<<fufuhang()<<".000000";
	return 0;
}