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From: Arno Welzel <usenet@arnowelzel.de>
Newsgroups: comp.lang.php
Subject: Re: break foreach loop after certain iteration and then start it
Date: Sat, 5 Mar 2016 10:52:36 +0100
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Thomas 'PointedEars' Lahn schrieb am 2016-03-05 um 02:28:

> Arno Welzel wrote:
> 
>> <?php
>> $counter = 0;
>>
>> foreach($mylist as $element)
>         ^^
>> {
>>     // Do something with $element
>>
>>     // Add something every three elements
>>     $counter++;
>>     if($counter==3)
>        ^^
> Flow control statements should not be written like function calls.

Which is a matter of style. I recognize flow control statements also
when they are not formatted with a space preceding the first bracket ;-).

But for beginners it may be helpful to distinguish between function
calls and flow control.

>>     {
>>         echo '<div id="logo"></div>';
>>         $counter = 0;
>>     }
>> }
> 
> One does not have to reset the counter if one uses the modulo operator, %, 
> to determine the indexes that are divisible by 3 without remainder.
> 
>   ++$counter;
>   if ($counter % 3 === 0)
>   {
>     …
>   }
> 
> or
> 
>   if (++$counter % 3 === 0)
>   {
>     …
>   }

Of course one can use modulo as well and use the index of the array in
combination with modulo as well. And yes - I know modulo and many other
things ;-)

But I doubt the OP understands "modulo". I just want to show the basic
idea behind it. Finding out what a modulo operator is and that this can
make things easier is something the OP should find out on his own -
because then it doesn't just copy & paste code he doesn't understand but
came to the knowledge by his own experience.

[...]
> Or, if this is too confusing,
> 
>     if (($index + 1) % 3 === 0)

You believe this is not confusing for beginners who ask how to achieve
the goal to do something every third step of an iteration?

This means:

1. You have to understand the syntax of foreach() in this example

2. You have to understand the modulo operator

3. You have to understand why (x+1) % 3 is zero for 0, 2, 5 etc.

When someone had enough knowledge to understand all this he would not
ask here how to do something every third iteration within a foreach() loop.


-- 
Arno Welzel
http://arnowelzel.de
http://de-rec-fahrrad.de
http://fahrradzukunft.de