CODEWITHSUNDEEP
javawhile-loop
Islam Assi
Islam Assi

Reputation: 1037

infinite while loop although the statement becomes false

This code give me infinite loop although sum become equals to 7 and become equals to (point)

while ( sum!=point || sum!=7)
{
    rollDices();
    System.out.println("rolling dices .. sum="+sum);
} //end while

but if I do this:

while(sum!=point)

or this 

while(sum!=7)

it works fine without any problem

Upvotes: 0

Views: 176

Answers (4)

RamonBoza
RamonBoza

Reputation: 9038

What happens to you is the following

the condition sum != point || sum!=7 always returns true if point != 7.

so think point = 12 and you get on sum 6.

6 != 12 -> true
6 != 7 -> true
true || true -> true

lets imagine you get 7 on sum

7 != 12 -> true
7 != 7 -> false
true || false -> true

Upvotes: 1

nhgrif
nhgrif

Reputation: 62052

If you're stuck and can't figure out why your || or && isn't doing what you want it to do, work out a "truth table".

For ||, the OR operator: 

true || false  //returns true
true || true   //returns true
false || true  //returns true
false || false //returns false

And for &&, the AND operator:

true && true   //returns true
true && false  //returns false
false && true  //returns false
false && false //returns false

Upvotes: 6

Scott Helme
Scott Helme

Reputation: 4799

Your logic is slightly flawed. Your statement is saying while sum is not equal to point or sum is not equal to 7. It will always be not equal to one of them, unless they are the same.

I think you wanted to use &&:

while(sum!=point && sum!=7){
    rollDices();
    System.out.println("rolling dices .. sum="+sum);
}

With the && once sum is equal to 7 or point it will exit the loop.

Upvotes: 5

Andrew_CS
Andrew_CS

Reputation: 2562

I'm assuming you wanted && instead of ||. This makes it so that when sum becomes equal to 7 it will get out of the loop.

while( sum!=point && sum!=7){
    rollDices();
    System.out.println("rolling dices .. sum="+sum);
}//end while

So the only time it will stay in the loop is when sum isn't equal to point and sum isn't equal to 7.

Also a side note - Are you sure you want sum != 7? Or is sum < 7 what you want in case sum became larger than 7?

Upvotes: 1

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