效果如下：

程序如下：

#include<iostream>

using namespace std;

int main(){

int a , b , c;

char d;

cin >> a >> d >> b;

if ( d == '+' ){

c = a + b;

cout << "=" << c << endl;

}

else if( d == '-' ){

c = a - b;

cout << "=" << c << endl;

}

else if( d == '/' ){

c = a / b;

cout << "=" << c << endl;

}

else if( d == '*' ){

c = a * b;

cout << "=" << c << endl;

}

else {

cout << "錯誤！" << endl;

}

}