代码如下：

#include <iostream>
using namespace std;
int main()
{
    int a,b;
    char ch;
    cin>>a>>ch>>b;
    if((ch=='+')||(ch=='-')||(ch=='*')||(ch=='/')||(ch=='%'))
    {
        switch (ch)
        {
            case '+':
                cout<<a+b<<endl;
                break;
            case '-':
                cout<<a-b<<endl;
                break;
            case '*':
                cout<<a*b<<endl;
                break;
            case '/':
                cout<<a/b<<endl;
            case '%':
                cout<<a%b<<endl;
        }
    }
    return 0;
}