Basic question about declaring variables/structures

Is there any difference between doing following declarations ? If so what are they? any benefits at all ?

Thanks in advance.

#1:

Code:

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main() {
  int i = 1;
  struct my_struct *s = NULL; 
}

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#2:

Code:

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main() {
  int i = 1;
  if(i) {
      struct my_struct *s = NULL; 
  }
}

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Did they teach you about variable scope yet? If so, and you've forgotten, or if not, you should go back and read that section again.


Quzah.

#2 has the profound disadvantage that at some point in your program you're going to get an error that the struct was never declared.

Whoever told you that was a good idea?

Quote:

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Originally Posted by CommonTater

Whoever told you that was a good idea?

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The same people that told you the other day that scattering variable declarations around was good. ;)


Quzah.

doh! *thud* head hits desk. heh, thanks.

Quote:

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Originally Posted by quzah

The same people that told you the other day that scattering variable declarations around was good. ;)


Quzah.

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Hey... watch which way you pointing that "Point of View" gun!!!

After all, he opened up a new scope to declare the variable!

Quote:

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Originally Posted by CommonTater

Hey... watch which way you pointing that "Point of View" gun!!!

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I was just pointing out the humor in you doing what he was doing, and then asking him who told him that doing what you were doing was a good idea.


Quzah.

Quote:

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Originally Posted by quzah

I was just pointing out the humor in you doing what he was doing, and then asking him who told him that doing what you were doing was a good idea.


Quzah.

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Well, there is a difference :D ... When I do it, it works.

I create mid-function scopes very deliberately and never declare variables anywhere but the very top of a scope.

It's as close to nested functions as you're gonna get in C.

I wasn't debating if it was deliberate or not. I assumed this was a simple exercise to teach scope. You both were doing the same exact thing, so I found it amusing that you were frowning upon the act you were partaking in.


Quzah.

Quote:

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Originally Posted by quzah

I wasn't debating if it was deliberate or not. I assumed this was a simple exercise to teach scope. You both were doing the same exact thing, so I found it amusing that you were frowning upon the act you were partaking in.
Quzah.

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Oh, I see... well, doc yourself 3 points and carry on... LOL.

EDIT: In my own defense, I never told him not to do it... only that doing it that way wouldn't work.

Quote:

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Originally Posted by CommonTater

In my own defense, I never told him not to do it... only that doing it that way wouldn't work.

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Bad defense though, since doing it that way works when it makes sense and is done correctly, hence your own claim that "when I do it, it works".

Quote:

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Originally Posted by bnyec

Is there any difference between doing following declarations ? If so what are they? any benefits at all ?

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In this case the examples are so trivial and contrived and it makes no real difference either way, and the program has no net effect anyway. So, the difference is purely an educational one concerning scope, as quzah outlined to you in post #2. In a more complete program, the difference/benefit depends on the bigger picture of what you are trying to do.