infinite do while loop?

Question

I want to make a loop that will print wrong answer each time answer is not 1 2 3 or 4 .... and I want it to run infinitly, mine don't detect if the answer is right or wrong it just print out invalid answer, then asks again, then crash! I don't know why it does that.

Here's my code don't read the "text" part because it's in French just look a the code!

System.out.println("Veuillez Choisir 1 des 4 groupes alimentaires suivants: (1)Légumes et fruits , (2) Produit cérealiers , (3) Laits et Substitues , (4) Viandes et substitues :");
        System.out.println("\n");
    answer =  Clavier.lireIntLn();
    do {
        System.out.println("Votre choix est invalide");
         System.out.println("Veuillez Choisir 1 des 4 groupes alimentaires suivants: (1)Légumes et fruits , (2) Produit cérealiers , (3) Laits et Substitues , (4) Viandes et substitues :");
            answer =  Clavier.lireIntLn();
                continue;
        }while (answer<1 && answer>5);

I dont understand how a developer can use a do-while or continue is something awful. — nachokk
– nachokk, Commented Oct 4, 2013 at 22:04

BlackHatSamurai · Accepted Answer · 2013-10-04 22:01:51Z

3

First you need to remove the continue.

After you do that, you will need to deal with this:

while (answer<1 && answer>5)

This will never happen. You need to do this:

while (answer<1 || answer>5)

You can't have a number be less than 1 AND greater than 5.

answered Oct 4, 2013 at 22:01

BlackHatSamurai

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Comments

Philipp · Accepted Answer · 2013-10-04 22:00:50Z

1

The continue statement causes the program execution to jump back to do immediately without even evaluate the while-condition. That means the condition is never evaluated and the loop becomes infinite.

Remove the continue, and the loop will be left when the while-condition is false. Unfortunately it will always be false, because a value can't be below 1 and above 5. When you want to continue until the user inputs 5, then try

while (answer != 5)

When you want (as written) allow any answer except 1, 2, 3 or 4, do this

while(answer >= 1 && answer <= 4);

answered Oct 4, 2013 at 22:00

Philipp

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Comments

North-Pole · Accepted Answer · 2013-10-04 22:00:51Z

0

The code would be more like this:

do
{
    System.out.println("Veuillez Choisir 1 des 4 groupes alimentaires suivants: (1)Légumes et fruits , (2) Produit cérealiers , (3) Laits et Substitues , (4) Viandes et substitues :");
    System.out.println("\n");
    answer =  Clavier.lireIntLn();
    if( answer < 1 || answer > 4  )
    {
        //print your error message here
    }
}while(true)

answered Oct 4, 2013 at 22:00

North-Pole

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1 Comment

North-Pole Over a year ago

".. and i want it to run infinitly"

Kalel Wade · Accepted Answer · 2013-10-04 22:00:58Z

0

The continue prevents it from reaching the while statement. Remove it and it will hit the while condition.

answered Oct 4, 2013 at 22:00

Kalel Wade

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