Question

IN C++

Rather than clutter up the source code with blocks of essentially the same calculations or blocks of code controlled by IF then…else logic, we can move these blocks of code into one location that can be called from anywhere and anytime during the application’s execution, the “function”.

Functions can be passed “arguments”, one or more data values and return zero or one value to the calling routine Functions can call other separate functions or even themselves recursively.

1. User can manually enter two decimal values
2. Application will allow user to decide whether to:
   1. Add the two numbers, return the total (i.e. n1 + n2) and display in the main
   2. Subtract Second number from the First number (i.e. n1 – n2), return the difference and display it in the main
   3. Multiply the two numbers, return the product (i.e. n1 * n2) and display it in the main
   4. Divide the First number by the Second number (i.e. n1 / n2), return the dividend and display it in the main.

If the divisor, n2, is zero, display a message, “Cannot divide by zero” in the function, default n2 to 1, return the dividend and display it in the main.

2. 5. Call all the above functions (add, subtract, multiply, divide) from one “combined” function. Display results in this function (why is this?). Do not call the add, subtract, multiply, divide functions separately in the main. Call them from one function (“function calling other functions”)
   6. Change the values WITHOUT quitting the application
3. Allow the user to run this application until they decide to quit.

Example Output:

1 of 2 - Enter First Number: 12.34

2 of 2 - Enter Second Number: 8.4

1 - Add (12.34 + 8.4)

2 - Subtract (12.34 - 8.4)

3 - Multiplication (12.34 X 8.4)

4 - Divide (12.34 / 8.4)

5 – ALL

6 – Change Values

7 - Quit

        Enter an Option (1 to 7): 3

12.34 X 8.4 = 103.656

Hit Any Key to continue...

1 - Add (2.4 + -3.4)

2 - Subtract (2.4 - -3.4)

3 - Multiplication (2.4 X -3.4)

4 - Divide (2.4 / -3.4)

5 - ALL

6 - Quit

        Enter an Option (1 to 7): 5

2.4 + -3.4 = -1

2.4 - -3.4 = 5.8

-3.4 - 2.4 = -5.8

2.4 X -3.4 = -8.16

2.4 / -3.4 = -0.705882

Hit Any Key to continue...

Answer 1

Code

#include<iostream>
using namespace std;
void menu(double n1,double n2)
{
   cout<<"\n1 - Add ( "<<n1<<" + "<<n2<<" )"<<endl;
   cout<<"2 - Subtract ( "<<n1<<" - "<<n2<<" )"<<endl;
   cout<<"3 - Multiplication ( "<<n1<<" X "<<n2<<" )"<<endl;
   cout<<"4 - Divide ( "<<n1<<" / "<<n2<<" )"<<endl;
   cout<<"5 - ALL"<<endl;
   cout<<"6 - Change Values"<<endl;
   cout<<"7 - Quit"<<endl;
   cout<<"\tEnter an Option (1 to 7):";
}
double Add(double n1,double n2)
{
   return n1+n2;
}
double Sub(double n1,double n2)
{
   return n1-n2;
}
double Mul(double n1,double n2)
{
   return n1*n2;
}
double Div(double n1,double n2)
{
   if(n2==0)
   {
       cout<<"Cannot divide by zero"<<endl;
       n2=1;
   }
   return n1/n2;
}
int main()
{
   double num1,num2;

   cout<<"1 of 2 - Enter First Number: ";
   cin>>num1;
   cout<<"2 of 2 - Enter First Number: ";
   cin>>num2;
   int choice;
   while (true)
   {
       menu(num1,num2);
       cin>>choice;
       cout<<endl;
       if(choice==1)
       {
           cout<<num1<<" + "<<num2<<" = "<<Add(num1,num2)<<endl;
       }
       else if(choice==2)
       {
           cout<<num1<<" - "<<num2<<" = "<<Sub(num1,num2)<<endl;
       }
       else if(choice==3)
       {
           cout<<num1<<" * "<<num2<<" = "<<Mul(num1,num2)<<endl;
       }
       else if(choice==4)
       {
           cout<<num1<<" / "<<num2<<" = "<<Div(num1,num2)<<endl;
       }
       else if(choice==5)
       {
           cout<<num1<<" + "<<num2<<" = "<<Add(num1,num2)<<endl;
           cout<<num1<<" - "<<num2<<" = "<<Sub(num1,num2)<<endl;
           cout<<num1<<" * "<<num2<<" = "<<Mul(num1,num2)<<endl;
           cout<<num1<<" / "<<num2<<" = "<<Div(num1,num2)<<endl;
       }
       else if(choice==6)
       {
           cout<<"1 of 2 - Enter First Number: ";
           cin>>num1;
           cout<<"2 of 2 - Enter First Number: ";
           cin>>num2;
       }
       else if(choice==7)
           break;
       else
           cout<<"Invalid choice\n";
   }
   return 1;
}

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