Re: how to get out from the outer for - C# Discussion Boards

Simon P Stevens17-Mar-09 0:29

Simon P Stevens

17-Mar-09 0:29

You can't (See the reply from XMen)

You could consider restructuring the loop to use a while loop instead. You might find if you structure it differently that you don't need the break.

Simon

Eslam Afifi17-Mar-09 0:40

Eslam Afifi

17-Mar-09 0:40

I suggest you go for the goto suggestion. While goto is discouraged, I find it helpful sometimes. It may even simplify the code more than what another structure would do. In this case, IMHO, it will (depending on the context too). A go to will not cost you an extra boolean value and saves an extra if statement.

Eslam Afifi

Pete O'Hanlon17-Mar-09 0:53

17-Mar-09 0:53

Your question shows that you have a misunderstanding of what a for loop actually does. I cringe whenever I see people use break statements inside for loops because it shows they've just gone for convenience without actually considering what they are trying to do.

A for loop is used to iterate a predictable and set number of times; that's what it's for (pardon the pun). If you need to iterate an indeterminate number of times, then you should consider using a boolean based loop structure, i.e. while ... do or do ... while instead (and yes - I know that a for loop is boolean based in that the exit condition is satisfied when you reach the to value in the count). Then, your logic makes more sense because you've based your exit on the condition you're testing.

Please, consider redoing your looping mechanism to a one that's a better fit. Whenever I see people recommending break or goto statements, I know that they are being lazy or have given no thought to what the proper use of the loop should be.

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Colin Angus Mackay17-Mar-09 0:58

Colin Angus Mackay

17-Mar-09 0:58

Best answer ever!

Simon P Stevens17-Mar-09 1:30

Simon P Stevens

17-Mar-09 1:30

I've looked really hard, but I can't find a '6' button anywhere, so unfortunately I'm only going to be able to vote you a 5. Sorry about that.

Fantastic.

Simon

Xmen Real 17-Mar-09 2:46

Xmen Real

17-Mar-09 2:46

Pete O'Hanlon wrote:
I know that they are being lazy or have given no thought to what the proper use of the loop should be.

Well well well, first of all I'm not lazy... and by reading your answer, people will thing .Net Framework developer were fool because they made 'break'. Perhaps the programmers they use 'continue' are lazy too.
Now, take an example...you need to iterate an array until you got a value hmm... 9. Now how you gonna do

for (int a=0; a < arrayx.Length; a++)
{
if (arrayx[a] == 9)
break;
}

bool foundNine = false;
int index = 0;
while(!foundNine)
{
if (arrayx[index] == 9)
foundNine = true;
index++;
}

I'll always prefer the first one...I dunno about you, it may look you a work of lazy coder.

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Pete O'Hanlon17-Mar-09 2:57

17-Mar-09 2:57

Xmen wrote:
Well well well, first of I'm not lazy

Perhaps not, but you aren't thinking about proper use of language constructs - hence my original comment.

int index = 0;
while (arrayx[index++] != 9)
{
}

That's how you'd do your example - now, you can justify yourself as long as you like but you are promoting a bad practice. Now, let's extend your sample to see why it's bad practice.

bool foundNine = false;
for (int i = 0; i < array.length; i++)
{
  if (array[i] == 9)
  {
    foundNine = true;
    break;
  }
}

if (foundNine && SomeOtherCondition())
{
  DoSomething(array[i]); // Oh, wait a second you can't do this here because you don't know what i is
}

Contrast this with:

int index = 0;
bool foundNine = false;
do
{
  if (array[index] == 9)
  {
    foundNine = true;
  }
  else
  {
    index++;
  }
} while (!foundNine);
if (foundNine && SomeOtherCondition())
{
  DoSomething(array[index]);
}

I don't know about you, but this doesn't feel like such a horrible hack.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

Xmen Real 17-Mar-09 3:00

Xmen Real

17-Mar-09 3:00

aha nice done...but 'break' isnt worthless

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Pete O'Hanlon17-Mar-09 3:29

17-Mar-09 3:29

All I ask is that you've considered the alternatives and given some thought to them - there are few absolute rules in programming, but it is important that you can actually justify why you've used a particular construct.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

Xmen Real 17-Mar-09 3:35

Xmen Real

17-Mar-09 3:35

Pete O'Hanlon wrote:
All I ask is that you've considered the alternatives and given some thought to them

nope you didnt.
"I cringe whenever I see people use break statements inside for loops because it shows they've just gone for convenience without actually considering what they are trying to do."

"Whenever I see people recommending break or goto statements, I know that they are being lazy or have given no thought to what the proper use of the loop should be."

plus you did unfair, you change the while loop to good one but messed up the for loop

here is mine

bool foundNine = false;
int i = 0
for (; i < array.length; i++)
{
  if (array[i] == 9)
  {
    foundNine = true;
    break;
  }
}

if (foundNine && SomeOtherCondition())
{
  DoSomething(array[i]); // Oh, wait a second I can use it
}

still better than while

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Pete O'Hanlon17-Mar-09 3:42

17-Mar-09 3:42

No it's not. You've now introduced obscurity for maintenance coding. Where's i declared in your loop? Outside - that's where. Your example is now even more confusing, and I'd rip your code apart in a code review if you did that while working for me.

You're not going to convince me that you can come up with a decent reason to ignore the fact that a while loop wouldn't be a better fit here, and it's obvious to me that you aren't willing to consider that your coding practice could possibly be less accurate, so I'm going to break off this discussion now before it becomes he said/she said.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.