for loop vs while loop

[Harikrishna Gorrepati]

Hi,

What is the difference between for loop and while loop when we can get same result, why do we need second loop..What makes one loop better than the other one.

public class LoopTest
{
	public static void main(String[] args)
	{
		for(int x=0; x<3; x++)
			System.out.println("x values is " + x);
		
		int y = 0;
		while(y < 3)
		{
			System.out.println("y value is " + y);
			y++;
		}
	}
}

Output is:

x values is 0
x values is 1
x values is 2
y value is 0
y value is 1
y value is 2

[Ankit Garg]

For loop is better for iterating over indexed items like arrays...

[Harikrishna Gorrepati]

We can get the same functionality with while loop also..I may have to change the question. Which feature one loop has while the other loop doesn't have it. What I am trying to get is, Do we miss anything if we get rid of one of the loops from Java ?

[Ram Narayan.M]

Seconding Ankit's...

For loop is more suitable for iterating over arrays... If you use for loop for iteration of arrays, it will be catchy and understandable rather than while loop.

And While loop can be used in the context on which a loop has to be executed until certain condition is reached...

E.g.,

Reading contents from a file until EOF character is reached... Here while loop is apt one...

[Ankit Garg]

There is no missing functionality in any of the loops. Its just that using for loop for iterating index elements is easier. Using while loop for the same functionality is possible but the code is ugly and harder to understand for anyone...

[Shanky Sohar]

if you want to make a code that is more understandable for future developer who see your code and be thankful to you then use for loop

[Bear Bibeault]

Shanky Sohar wrote:if you want to make a code that is more understandable for future developer who see your code and be thankful to you then use for loop

Not correct. Let me fix it:

"If you want to write code that is more understandable for both yourself and for future developers who see your code and be thankful to you, then use whichever loop type makes the most sense in the context of the code."

Sometimes the for loop will be the most readable, sometimes it will be the while loop. Use whechever makes the most sense -- but that's certainly not always the for loop.

[Shanky Sohar]

Thanks for correcting...
But what i mean is for Array elements only...

[Bear Bibeault]

Shanky Sohar wrote:But what i mean is for Array elements only...

Agreed, that is one of the purposes for which a for loop would most likely be the most appropriate choice.

[Shanky Sohar]

Thanks..........

[Seetharaman Venkatasamy]

if you want to keep on running a loop, until certain condition meet . then while loop is my choice rather than for loop.

For an example:

    
while(true)
{
  n = n / 2;
  if(n == 2)
 {
      return;
 }
}

[Mina Daoud]

Use for loop if you know how many iterations you will need. Use while loop if you don't know how many iterations are required!

[Piotr Nowicki]

For loops should be generally prefered over while, as they are easier to understand and more intuitive.

AFAIR, Bruce Eckel suggested that the for loop should be also prefered because of the granularity of the variables. For loop lets you declare, define and use iteration variable only within the for, which conforms the choose-smallest-available-scope for the variable rule.