help with looping

[Olaoluwa Odusegun]

I was learning looping in Java and decided to try this code and then I encountered an endless loop of 2s. why is that? Can someone explain to me. I believe this line count=count++ caused it.

class ForDemo{
public static void main(String []args){
int count;

for(count=2;count<=5;count=count++)
System.out.println("count is:"+count);
System.out.println("Done!");
      }
  }

[Knute Snortum]

Check your braces {}

[Arthur Vinicius Rebelo]

Use a prefix increment like this : count = ++count. Or even better just count++

[Knute Snortum]

It isn't a brace mismatch like I first thought. The problem is the third part of your for loop.

[Knute Snortum]

Posted at the same time!

[Knute Snortum]

To see what's happening here and why, try this code:

public class ForDemo {
	public static void main( String[] args ) {
		int count = 2;
		count = count++;
		System.out.println(count);
		count = count++;
		System.out.println(count);
        }
}

What's the output? Now try this:

public class ForDemo {
	public static void main( String[] args ) {
		int count = 2;
		count++;
		System.out.println(count);
		count++;
		System.out.println(count);
        }
}

Now try this:

public class ForDemo {
	public static void main( String[] args ) {
		int count = 2;
		System.out.println(count++);
        }
}

Lastly try this:

public class ForDemo {
	public static void main( String[] args ) {
		int count = 2;
		System.out.println(++count);
        }
}

count++ says "use" the variable and then increment. In count = count++, it will evaluate count, which is two, and then increment it. But then you're setting count to two immediately. Basically, count = count++ is never what you want, just count++ or ++count.

[Campbell Ritchie]

Welcome to the Ranch

That is a common error which arises from a misunderstanding about how i++ works.
You will see loops written in books like this:-

for (int i = 0; i < j; i++)
{
   ...
}

and like this:-

for (int i = 0; i < myArray.length; i++)
{
   ...
}

There are good reasons for sticking to the conventional formats, and one of the good reaosns is this:-
Those loops always work

[Campbell Ritchie]

A few minutes ago, I wrote: . . . That is a common error . . .

But I don't remember seeing it in a loop quite like that.
Always keep your loop headings nice and simple. You may come across things like this:

int sum = 0;
for (int i = 0; i <= 10; sum += i++);
System.out.println(sum);

That sort of code was popular with C programmers 40 years ago because it is very concise, but it is very difficult to understand, so I won't even bother explaining it. I shall simply tell you to avoid that sort of code, even though it will happily run in Java®.