13.cpp

// calculator switchcase program
#include<iostream>
using namespace std;
int main(){
    int op;
    double n1,n2,ans;
    cout<<"----Menu Driven Calculator----\n";
    cout<<"Enter the first number: ";
    cin>>n1;
    cout<<"Enter the second number: ";
    cin>>n2;
    cout<<"Select the desired operation below:\n";
    cout<<"1.Addition\n2.Subtraction\n3.Multiplication\n4.Division\n";
    cin>>op;
    switch(op){
        case 1:
            ans=n1+n2;
            cout<<"Sum = "<<ans;
            break;
        case 2:
            ans=n1-n2;
            cout<<"Difference = "<<ans;
            break;
        case 3:
            ans=n1*n2;
            cout<<"Product = "<<ans;
            break;
        case 4:
        if(n2!=0){
            ans=n1/n2;
            cout<<"Quotient = "<<ans;
        }else{
            cout<<"Error: division by zero!";
        }
            break;
        default:
            cout<<"Invalid choice.";
    }
    return 0;
}