How do I fix my do-while-loop so that it doesnt infinite loop when x=0

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Should be a tiny problem that should easily be solved. My code works fine when x is assigned a value over 0, but when it is assigned 0 it either just prints "+" if i use while (x > 0); or if i use while (x != 0); it just infinite loops.

Any help would be very kind, thanks in advance!

What I have tried:

	public static void runLoop(int x){
		
		do {
			System.out.print("+");
			 x--;

		}
		while (x > 0); 

}

I also tried while (x != 0) but that seems to not work because x just skips 0 and it becomes an infinite loop when x is assigned the value 0.

public static void runLoop(int x){

    while(x !=0){
        System.out.print("+");
        x--;
    }
}

Looks like this when I did it in normal while-loop and it feels like i converted it right.

Posted 16-Jun-21 9:32am

Rari0002

Updated 16-Jun-21 10:21am

v3

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2 solutions

Solution 2

Java

while (x !=0)
{
    System.out.print("+");
    if (x < 0)
        x++;
    else
        x--;
}
System.out.println(" ");

Posted 16-Jun-21 10:21am

Richard MacCutchan

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OriginalGriff · Accepted Answer · 2021-06-16T09:53:00

Solution 1

I tried it here with an online compiler and it does what I expected: pass it 0 and it prints one "+" character.

I suspect that either the code that calls that is the problem, or that isn;t the code you are executing.

And why do you have an empty curly bracket block after the while line? What do you expect that to do?

Posted 16-Jun-21 9:53am

OriginalGriff

Comments

Rari0002 16-Jun-21 16:21pm

Brackets are gone, don't know why they were there. I have tried switching around the "x--" but I can't seem to find the problem, it has worked fine with both a for loop and a normal while loop so I feel like it should work. They have different execution styles but don't know how that would affect this.

OriginalGriff 16-Jun-21 16:27pm

As I said, it works fine when I test it - so you need to look at the surrounding environment rather than that code in isolation.

OriginalGriff 16-Jun-21 16:27pm

What does the debugger show you is happening?

Rari0002 16-Jun-21 16:33pm

Oh sorry might have phrased the question a bit all over the place. I do not want the program to print out any "+" when x is assigned the value 0, I want it to print out a blank space.

OriginalGriff 16-Jun-21 16:39pm

Then you can't use a "do ... while" loop - the whole idea of those is that the test is executed after the loop body, not before: you always get at least one pass through the loop, even if the condition always evaluates to false.

Rari0002 16-Jun-21 16:44pm

That was what I thought, but this is an excercise from my school to improve so it feels odd that they would assign impossible tasks. It is not made as a trick question either so they may have messed up a little bit.

OriginalGriff 16-Jun-21 16:52pm

It can be done - just put an "if" test inside the loop and when it's true y=use break to exit. The do ... while condition can then be "true" instead of a "genuine test".

But that's a bollocks way to do it and definitely not an improvement on a while or for loop! :laugh:

Rari0002 16-Jun-21 17:06pm

public static void runLoop(int x){

do {
if (x == 0)
break;
x--;
System.out.print("+");

}while (x > 0);
}

Thank you so much, managed to find a way :D

Rari0002 16-Jun-21 16:33pm

The infinite loop code part is under the first code, I have mentioned it as text rather than in the code.

OriginalGriff 16-Jun-21 16:39pm

Don't add text that describes problems the code you show doesn't have! :laugh: