Ask the user if they want to rerun the program?

[morganniie]

The problem is, we have to modify the code to ask the user if they want to run the program again. I already have a do-while loop set up, but I'm not sure where to put my variable as every time it says that I'm using an uninitialized variable.

#include <iostream>
using namespace std;

int main()
{
    const double PI = 3.14159;

    int    choice;         // User's shape choice
    double radius,         // Circle radius
           length,         // Rectangle length
           width,          // Rectangle width
           base,           // Triangle base
           height,         // Triangle height
           area;           // Area of the selected shape
	char   input;		   // User's rerun choice


	// Display selections and request user input
	cout << "Geometry Calculator\n\n";
	cout << "1. Calculate the area of a Circle\n";
	cout << "2. Calculate the area of a Rectangle\n";
	cout << "3. Calculate the area of a Triangle\n";
	cout << "4. Quit\n\n";
	cout << "Enter your choice (1-4): ";
	cin >> choice;

	// Calculate and display the area of the selected shape
	do
	{
		char input;
		switch (choice)
		{
		case 1:  // Area of a circle
			cout << "\nEnter the circle's radius: ";
			cin >> radius;

			if (radius < 0)
				cout << "\nThe radius can not be less than zero.\n";
			else
			{
				area = PI * radius * radius;
				cout << "\nThe area is " << area << endl;

				break;
			}

		case 2:  // Area of a rectangle
			cout << "\nEnter the rectangle's length: ";
			cin >> length;
			cout << "Enter the rectangle's width: ";
			cin >> width;

			if (length < 0 || width < 0)
				cout << "\nOnly enter positive values for length and width.\n";
			else
			{
				area = length * width;
				cout << "\nThe area is " << area << endl;
			}
			break;

		case 3:  // Area of a triangle
			cout << "Enter the length of the base: ";
			cin >> base;
			cout << "Enter the triangle's height: ";
			cin >> height;

			if (base < 0 || height < 0)
				cout << "\nOnly enter positive values for base and height.\n";
			else
			{
				area = base * height * 0.5;
				cout << "\nThe area is " << area << endl;
			}
			break;

		case 4:	 cout << "\nBye!\n";
			break;

		default:  cout << "\nYou may only enter 1, 2, 3, or 4.\n";
		}
	} while (input == 'y');
	return 0;
}

[morganniie]

So i figured that out, but now I'm not sure how to change it so if the user inputs choice 4 it doesn't show the "Do you want to run it again?". 4 is the quit the program option so i dont want it to ask if they want to rerun it.

#include <iostream>
using namespace std;

int main()
{
    const double PI = 3.14159;

    int    choice;         // User's shape choice
    double radius,         // Circle radius
           length,         // Rectangle length
           width,          // Rectangle width
           base,           // Triangle base
           height,         // Triangle height
           area;           // Area of the selected shape
	char   rerun;		   // User's rerun choice

	do
	{

		// Display selections and request user input
		cout << "Geometry Calculator\n\n";
		cout << "1. Calculate the area of a Circle\n";
		cout << "2. Calculate the area of a Rectangle\n";
		cout << "3. Calculate the area of a Triangle\n";
		cout << "4. Quit\n\n";
		cout << "Enter your choice (1-4): ";
		cin >> choice;

		// Calculate and display the area of the selected shape
		switch (choice)
		{
		case 1:  // Area of a circle
			cout << "\nEnter the circle's radius: ";
			cin >> radius;

			if (radius < 0)
				cout << "\nThe radius can not be less than zero.\n";
			else
			{
				area = PI * radius * radius;
				cout << "\nThe area is " << area << endl;
				break;
			}

		case 2:  // Area of a rectangle
			cout << "\nEnter the rectangle's length: ";
			cin >> length;
			cout << "Enter the rectangle's width: ";
			cin >> width;

			if (length < 0 || width < 0)
				cout << "\nOnly enter positive values for length and width.\n";
			else
			{
				area = length * width;
				cout << "\nThe area is " << area << endl;
			}
			break;

		case 3:  // Area of a triangle
			cout << "Enter the length of the base: ";
			cin >> base;
			cout << "Enter the triangle's height: ";
			cin >> height;

			if (base < 0 || height < 0)
				cout << "\nOnly enter positive values for base and height.\n";
			else
			{
				area = base * height * 0.5;
				cout << "\nThe area is " << area << endl;
			}
			break;

		case 4:	 cout << "\nBye!\n";
			break;

		default:  cout << "\nYou may only enter 1, 2, 3, or 4.\n";
		}
		cout << "\nDo you want to run that again? y/n: ";
		cin >> rerun;
	} while (rerun == 'y' || rerun == 'Y');
	return 0;
}

[Handy Andy]

Hello morganniie,

int main()
{
    const double PI = 3.14159;

    int    choice{};      // User's shape choice  // <--- ALWAYS initialize all your variables.
    double radius{},      // Circle radius
        length{},         // Rectangle length
        width{},          // Rectangle width
        base{},           // Triangle base
        height{},         // Triangle height
        area{};           // Area of the selected shape
    char   rerun{};       // <--- Or char rerun{'n'}; 

You could also include the header file "<cctype>" and say
while (std::toupper(rerun) == 'Y' or use tolower and a lower case "y".

Andy

[Handy Andy]

Hello morganniie,

After running your program give this a try for "case 4":

case 4:
    cout << "\nBye!\n";
    rerun = 'n';
    continue;
    break;

Case 4 should end the program not ask the user if they want another run.

Andy

[morganniie]

Yes!! That worked thank you so much. I didn't really understand what you were talking about in the first post, (I'm only in week 4 of Principles of Programming) but that does make sense.

[Handy Andy]

Hello morganniie,

Always initialize your variables. You may be use to seeing int choice = 0;.

The {}s, or uniform initializer, started with the C++ 2011 standards. Empty it will initialize the variable to (0)zero based on the variable's type. In the case of a "double" it would be (0.0).

For "std::string"s they are empty when defined or between the {}s use double quotes around the string and for a "char" use single quotes as I did with "rerun".

Andy