C :

#include <stdio.h>
void main()
{
	float a,b,d;
	char c;
	scanf("%f%f",&a,&b);
	scanf(" %c",&c);
	switch(c)
	{
		case '+':d=a+b;break;
		case '-':d=a-b;break;
		case '*':d=a*b;break;
		case '/':d=a/b;break;
	}
	printf("%.2f\n",d);
}

C++ :

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
    double a,b,ans;
    cin>>a>>b;
    char op;
    cin>>op;
    switch (op)
    {
    case '+':
        ans=a+b;
        break;
    case '-':
        ans=a-b;
        break;
    case '*':
        ans=a*b;
        break;
    case '/':
        ans=a/b;
        break;    
    default:
        break;
    }
    printf("%.2lf\n",ans);
    return 0;
}

Pascal :

program xx;
var x,y,sum:real;
    ch: char;
begin
  readln(x,y);
  readln(ch);
  case ch of
  '+' :sum:=x+y;
  '-' :sum:=x-y;
  '*' :sum:=x*y;
  '/' :sum:=x/y;
  end;
  writeln(sum:3:2);
end.

Python :

# coding=utf-8
a, b = map(float, input().split())
operator = input()

if operator == '+':
    result = a + b
elif operator == '-':
    result = a - b
elif operator == '*':
    result = a * b
elif operator == '/':
    if b == 0:
        print("除数不能为0")
    else:
        result = a / b
else:
    print("错误的运算符")

if operator in ['+', '-', '*', '/']:
    print("%.2f" % result)