菜单驱动的C++程序，用于简单的计算器

问题陈述：
使用Switch案例编写一个菜单驱动程序，以计算以下内容：

1. 两个数的加法
2. 两个数字之间的差异
3. 两个数的乘积
4. 两个数的除法
5. 两个数字的HCF
6. 两个数字的LCM

例子：

Input: num1 = 5, num2 = 7, choice = 1
Output: Sum is 12

Input: num1 = 5, num2 = 7, choice = 5
Output: GCD is 1

执行：

// C++ program to illustrate
// Menu-Driven program using Switch-case
  
#include 
using namespace std;
  
// Function to display the menu
void menu()
{
    cout << "Press 1 to calculate Sum of Numbers\n";
    cout << "Press 2 to calculate Difference of Numbers\n";
    cout << "Press 3 to calculate Product of numbers\n";
    cout << "Press 4 to calculate Division of numbers\n";
    cout << "Press 5 to calculate HCF of numbers\n";
    cout << "Press 6 to calculate LCM of numbers\n";
    cout << "Press 7 to exit\n";
}
  
// Function to calculate and display the result
void result(int choice, int a, int b)
{
  
    // Display the result
    switch (choice) {
    case 1: {
        cout << "Sum is " << (a + b) << "\n";
        break;
    }
    case 2: {
        cout << "Difference is " << (a - b) << "\n";
        break;
    }
    case 3: {
        cout << "Product is " << (a * b) << "\n";
        break;
    }
    case 4: {
        cout << "Division is " << (a / b) << "\n";
        break;
    }
    case 5: {
        cout << "GCD is " << __gcd(a, b) << "\n";
        break;
    }
    case 6: {
        cout << "LCM is "
             << ((a * b) / __gcd(a, b))
             << "\n";
        break;
    }
    case 7: {
        cout << "Thank you\n";
        break;
    }
    default:
        printf("Wrong Input\n");
    }
}
  
int main()
{
  
    // Get the two numbers
    int a = 5, b = 7;
  
    int choice, res;
  
    // Display the menu
    menu();
  
    // Enter the choice
    cout << "Enter your choice:\n";
    choice = 1;
    cout << "Choice is " << choice << endl;
  
    // Display the result
    // according to the choice
    result(choice, a, b);
  
    return 0;
}

输出：

Press 1 to calculate Sum of Numbers
Press 2 to calculate Difference of Numbers
Press 3 to calculate Product of numbers
Press 4 to calculate Division of numbers
Press 5 to calculate HCF of numbers
Press 6 to calculate LCM of numbers
Press 7 to exit
Enter your choice:
Choice is 1
Sum is 12

时间复杂度： O(n)。