'for' v. 'while' loop...

ive been looking around the forums and i havent seen this one yet.
is a for loop better to use then a while loop?
are there situations when you would want to use one over the other?
or is it all syntax?
thanks in advance.
~M.I.

Quote:

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Originally Posted by MikeyIckey

ive been looking around the forums and i havent seen this one yet.

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Really? I thought it had been done to death.

Quote:

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Originally Posted by MikeyIckey

is a for loop better to use then a while loop?

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Yes. No. Use whichever fits the loop best. That is, if you are going from here to there, a for loop seems quite well suited for the task. If you are looping until some condition is met, a while loop may be better suited.

Quote:

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Originally Posted by MikeyIckey

are there situations when you would want to use one over the other?

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Preference to a degree. I'd say it mostly has to do with whether your loop needs an initial condition and/or specific "increment" or not.

cool, thanks for the insight!

Now you're gonna ask yourself, when should I use:

Code:

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while ( condition )
{
  ...
}

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and when should I use:

Code:

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do
{
  ...
} while ( condition )

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;)

It used to be that for-loops where slightly better optimized (this is about 15 years ago, when compilers had to live in DOS where 640K was the limit, and non-PC machines has a few MB of RAM to share between different apps & users). In such a system, the compiler will not be able to do advanced optimizations that require building multiple large code-paths and check which is faster/better/shorter (whichever applies) - or if it did, it would make the compiler seriously slow, and whilst optimization is nice, having a compile that finishes the same day you started it is also useful.

Nowadays, using a modern compiler, if you do the same work, you most likely end up with the same code, as long as you go about it in a reasonably similar way.

Some "interesting" uses of for & while:

Code:

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    for(;;) ...    // same as while(1)
   
    for(p = head; p; p = p->next) ...  // Walk through a linked list from head to tail. 
    // Same code using while...
    p = head;
    while(p)  {
        ...
        p = p->next;
    }
    for(i = 0; i < 10; i++)  ...
    // Same code using while using ugly coding style
    i = -1;
    while(i++, i < 10) ...
    // Alternatively:
    i = 0;
    while(i < 10) {
      ...
      i++;
    }

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Mats

thanks guys, i really appreciate the help.