Loop(s) assistance.

[Hyperbog]

Hey everybody. I have a practice question I am tackling from a beginners C++ book regarding loops (while, do-while, & for), and would like to know if I am approaching this correctly and if I can simplify my code to include fewer lines.

Here is the question from the book:

"Write a menu program that lets the user select from a list of options, and if the input is not one of the options, reprint the list."

Here is my code:

#include <iostream>
#include <string>

using namespace std;

int main()
{
    string  a = "1", b = "2", c = "3", d = "4";
    string input;
    do
    {
        cout << "Choose from one of the following four choices: \n";
        cout << a << ": This is choice 1.\n" << b << ": This is choice 2.\n" << c << ": This is choice 3.\n" << d << ": This is choice 4.\n";
        cout << "Enter your choice: ";
        cin >> input;

    if (input == "1")
        {
            cout << "Your choice is 1.\n";
            break;
        }
    if (input == "2")
        {
            cout << "Your choice is 2.\n";
            break;
        }
    if (input == "3")
        {
            cout << "Your choice is 3.\n";
            break;
        }
    if (input == "4")
        {
            cout << "Your choice is 4.\n";
            break;
        }
    cout << "\n";
    }
    while (1);
}

[Hyperbog]

It looks like when I posted this the formatting changed a bit. I copied it straight from my compiler, however, it doesn't look quite like this. My apologies.

[wildblue]

If you edit your post, highlight your code, then click the <> button in the Format palette on the right side of the post, that will format your code on the forum.

[Hyperbog]

Fixed the format. Looks readable now. Thanks.

[wildblue]

If they're entering a single number, I'd probably make the input type a char or int. You don't really need the separate variables for each option, at least in this program. You can have the while condition check for entries outside of the 1 to 4 range. I took out all the separate break statements. Instead of an if/else statements, you could also do this with a switch statement.

#include <iostream>
using namespace std;

int main()
{
    char input;
    do
    {
        cout << "Choose from one of the following four choices: \n";
        cout << "1.This is choice 1.\n2.This is choice 2.\n3.This is choice 3.\n4.This is choice 4.\n";
        cout << "Enter your choice: ";
        cin >> input;

		if (input == '1')
			cout << "Your choice is 1.\n";
		else if (input == '2')
			cout << "Your choice is 2.\n";
		else if (input == '3')
			cout << "Your choice is 3.\n";
		else if (input == '4')
			cout << "Your choice is 4.\n";
		else
			cout << "I don't recognize that choice. Please try again.\n";
    }while (input < '1' || input > '4');
    
    return 0;
}

[Hyperbog]

Thanks. This helps me think of different ways to execute code in situations like this. I initially tried to use the "or" operator as well, but with no success, and I like to the use of the ">" sign. Much appreciated for the response and assistance.

[redsuns]

i would do this

#include <iostream>
using namespace std;

int main()
{
    char input;
    do
    {
        cout << "Choose from one of the following four choices: \n";
        cout << "1.This is choice 1.\n2.This is choice 2.\n3.This is choice 3.\n4.This is choice 4.\n";
        cout << "Enter your choice: ";
        cin >> input;

		if(input < '1' && input > '4' )
		cout << "I don't recognize that choice. Please try again.\n";

    }while (input > '1' && input < '4');

                if (input == '1')
			cout << "Your choice is 1.\n";
		else if (input == '2')
			cout << "Your choice is 2.\n";
		else if (input == '3')
			cout << "Your choice is 3.\n";
		else if (input == '4')
			cout << "Your choice is 4.\n";
    
    return 0;
}

[redsuns]

you can also add another do-while asking if you want to rerun the program.

[Hyperbog]

Thanks as well for the response. I'm going to experiment with what you both have recommended to practice a bit more with not only this particular exercise, but other loop scenarios as well.

[robkar32]

You could make it much smaller, but then it would just look bad. That's not what it's all about. I like having readable code. This is how i would do it btw. Switch cases instead of a bunch of if and else if statements.

#include <iostream>
#include <windows.h>

using namespace std;

int main(){

    unsigned int iInput;

    cout << "Select an option" << endl;

    for(unsigned char i = 1; i <= 4; i++)
        cout << "This is choice: " << static_cast<int>(i) << endl;

    cin >> iInput;

    switch(iInput) {

        case 1: {
            cout << "Your choice is 1.\n" << endl;
            break;
        }
        case 2: {
            cout << "Your choice is 2.\n" << endl;
            break;
        }
        case 3: {
            cout << "Your choice is 3.\n" << endl;
            break;
        }
        case 4: {
            cout << "Your choice is 4.\n" << endl;
            break;
        }
        default:
            for(unsigned char i = 1; i <= 5; i++)
            {
                system("CLS");
                cout << "Could not recognize choice. Please try agian in " << static_cast<int>(i) << " seconds" << endl;
                Sleep(1000);
                system("CLS");
            }
            main();
    }
}

[wildblue]

line 43 main();

Main function shouldn't be called within a program.