Is there a way to limit how many characters a user can input?

[snowl0l]

So I'm using a book to help me learn c++ and I'm very new to it. The exercise it's telling me to do is to write a program that lets the user select from a list of options, and if the input is not one of the options, reprint the list.

The problem I am facing is that I don't want the user to be able to input multiple characters at once. Basically, I want to limit the user to once character. So if he types ACD, he gets an invalid response reply. Is there a way to limit how many characters he can input?

#include <iostream>
#include <string>

using namespace std;

int main()
{
    char answer = ' ';
    cout << "Hello, user. Welcome to your life. It's the morning." << endl;
    cout << '\n';
    while(answer != 'a' || answer != 'A' || answer != 'b' || answer != 'B' || answer != 'c' || answer != 'C' || answer != 'd' || answer != 'D')
    {
        cout << "Would you like to: " << endl;
        cout << "A. Eat some cereal." << endl;
        cout << "B. Get dressed." << endl;
        cout << "C. Go pee." << endl;
        cout << "D. Take a shower." << endl;
        cout << '\n';
        cout << '\n';
        cout << '\n';
        cout << "Please choose your answer: " << endl;
        cin >> answer;
        cout << '\n';
        if(answer == 'a' || answer == 'A')
        {
            cout << "Alright, let's go eat some cereal." << endl;
            break;
        }
        if(answer == 'b' || answer == 'B')
        {
            cout << "Alright, put some clothes on then. Pussy" << endl;
            break;
        }
        if(answer == 'c' || answer == 'C')
        {
            cout << "Alright, go pee then. Nobody's stopping you." << endl;
            break;
        }
        if(answer == 'd' || answer == 'D')
        {
            cout << "Good. You stink." << endl;
            break;
        }
        else
        {
            cout << "Your answer was incorrect. Please try again." << endl;
            cout << '\n';
        }
    }
}

[cire]

Is there a way to limit how many characters he can input?

Not in standard C++.

Btw, the condition in your while loop is wrong.

The truth table for logical or looks like this:

 v1    v2   | result
--------------------
true  true  | true
true  false | true
false true  | true
false false | false

So, the only way while (answer != 'a' || answer != 'A') will be false
is when answer is equal to both 'a' and 'A', which isn't possible.

[snowl0l]

@cire

so should I just not worry about it for now since it's an exercise? Will I learn more about limiting characters later on?

[cire]

so should I just not worry about it for now since it's an exercise?

I wouldn't.

Will I learn more about limiting characters later on?

Not in standard C++, but of course you're certainly welcome to delve into system specific methods or third party libraries which enable it.

[snowl0l]

@cire

Would this be any better:

while(answer != 'a' || answer != 'A', answer != 'b' || answer != 'B', answer != 'c' || answer != 'C', answer != 'd' || answer != 'D')

Or is this still wrong? How would you set it up?

[Mr Impact]

This would look a bit better.

#include <iostream>
#include <string>
#include <ctype.h> // to use toupper(char)

using namespace std;

int main()
{
	char answer = ' ';
	cout << "Hello, user. Welcome to your life. It's the morning.\n\n";
	while (answer != 'A' || answer != 'B' || answer != 'C' || answer != 'D')
	{
		cout << "Would you like to:\n";
		cout << "A. Eat some cereal.\n";
		cout << "B. Get dressed.\n";
		cout << "C. Go pee.\n";
		cout << "D. Take a shower.\n\n\n";
		cout << "Please choose your answer:\n";
		cin >> answer;
		answer = toupper(answer);
		cout << endl;
		
		switch (answer)
		{
			case 'A':
				cout << "Alright, let's go eat some cereal." << endl;
				break;
			break;

			case 'B':
				cout << "Alright, put some clothes on then. Pussy" << endl;
				break;
			break;

			case 'C':
				cout << "Alright, go pee then. Nobody's stopping you." << endl;
				break;
			break;

			case 'D':
				cout << "Good. You stink." << endl;
				break;
			break;

			default: cout << "Your answer was incorrect. Please try again.\n\n";	;
		}
	}
}

[snowl0l]

@Mr Impact
this has helped me a lot.

Although, my book hasn't gone over switch statements yet so I don't want to use switch statements because that would be cheating.

I ended up making something like this:

#include <iostream>
#include <string>
#include <ctype.h> //I didn't know I needed a separate library to use tolower. Thanks!

using namespace std;

int main()
{
    char answer = ' ';
    cout << "Good morning. Welcome to the game of life. What will you do first?" << endl;
    cout << endl;
    do
    {
    cout << "Please select an option: " << endl;
    cout << '\n';
    cout << '\n';
    cout << "A.    Eat some breakfast." << endl;
    cout << "B.    Take a shower." << endl;
    cout << "C.    Take a piss." << endl;
    cout << "D.    Eat a banana!" << endl;
    cout << '\n';
    cout << '\n';
    cin >> answer;
    answer = tolower(answer);
    cout << '\n';
        if(answer == 'a')
        {
            cout << "Alright, let's go eat some breakfast!" << endl;
        }
        if(answer == 'b')
        {
            cout << "Alright, go take a shower. It's good to stay clean." << endl;
        }
        if(answer == 'c')
        {
            cout << "Hey man you do what you gotta do... " << endl;
        }
        if(answer == 'd')
        {
            cout << "Alright. Bananas are cool." << endl;
        }
        else
        {
            cout << "Sorry, none of your answer choices were valid. Please try again." << endl;
            cout << '\n';
            cout << '\n';
        }
    } while (answer != 'a' && answer != 'b' && answer != 'c' && answer != 'd');

    return 0;




}

The only problem I'm having now is that for some reason, the else statement is executed no matter what


jk fixed it by replacing if with else if.

[TheIdeasMan]

Hi,

I have a pathological hate for constructs like this:

} while (answer != 'a' && answer != 'b' && answer != 'c' && answer != 'd');

Instead, consider using a bool variable to control a while loop:

bool Quit = false;

while (!Quit) {
    // show menu with a quit option
   std::cin >> answer;
    answer = std::tolower(answer);
    std::cout << '\n';
        if(answer == 'a')
        {
            std::cout << "Alright, let's go eat some breakfast!\n";
        }
        else if(answer == 'b')
        {
            std::cout << "Alright, go take a shower. It's good to stay clean.\n";
        }
        else if(answer == 'c')
        {
            std::cout << "Hey man you do what you gotta do...\n ";
        }
        else if(answer == 'd')
        {
            std::cout << "Alright. Bananas are cool.\n";
        }

        else if (answer =='q')
        {
            Quit = true;
        }
        else
        {
            std::cout << "Sorry, none of your answer choices were valid. Please try again.\n\n";
        }
}