How can I iterate through two arrays at the same time without re-iterating through the parent loop?

Question

How can I iterate through two arrays at the same time that have equal sizes ?

for example , first array $a = array( 1,2,3,4,5); second array $b = array(1,2,3,4,5);

The result that I would like through iterating through both is having the looping process going through the same values to produce a result like

I tried to do it this way below but it didn't work , it keeps going through the first loop again

foreach($a as $content) {
    foreach($b as $contentb){
        echo $a."-".$b."<br />"; 
    }
}

Are these arrays indexed the same way? Then just iterate over the index... `for ($ii=...)` — Floris, Mar 18 '13 at 21:38
possible duplicate: [php looping through multiple arrays](http://stackoverflow.com/q/9171488/367456) — hakre, Jun 23 '13 at 11:58

score 24 · Answer 1 · answered Mar 18 '13 at 21:38

24

Not the most efficient, but a demonstration of SPL's multipleIterator

$mi = new MultipleIterator();
$mi->attachIterator(new ArrayIterator($a));
$mi->attachIterator(new ArrayIterator($b));

$newArray = array();
foreach ( $mi as $value ) {
    list($value1, $value2) = $value;
    echo $value1 , '-' , $value2 , PHP_EOL;
}

answered Mar 18 '13 at 21:38

Mark Baker

209,507
32
346
385

And since PHP 5.5 (maybe sooner?) you can even do `foreach ($mi as [$value1, $value2])` – jirig Mar 20 '21 at 21:18
I like the object oriented approach – Danon Apr 05 '21 at 16:30
I didn't know this iterator and it's resolve my problem. Thank you, i approve your solution rather than one selected – Astro-Otter Apr 21 '21 at 12:21

Nick Andriopoulos · Accepted Answer · 2013-03-18T21:42:30.510

19

Use a normal for loop instead of a foreach, so that you get an explicit loop counter:

for($i=0; $i<count($content)-1; $i++) {
  echo $content[$i].'-'.$contentb[$i];
}

If you want to use string based indexed arrays, and know that the string indexes are equal between arrays, you can stick with the foreach construct

foreach($content as $key=>$item) {
  echo $item.'-'.$contentb[$key];
}

edited Mar 18 '13 at 21:42

answered Mar 18 '13 at 21:37

Nick Andriopoulos

10,313
6
32
56

won't work if he starts using arrays with string based indexes! – ITroubs Mar 18 '13 at 21:37
otherwise that's what i would have used too – ITroubs Mar 18 '13 at 21:38
@ITroubs added case for string based indexes, even though the example data in the question do not specify any need for this. – Nick Andriopoulos Mar 18 '13 at 21:42
3

Should be for($i=0; $i – Ravean Nov 22 '13 at 21:16
This doesn't work for arrays with different set of keys – Danon Apr 05 '21 at 16:31
@Danon second example works assuming arrays share length and element order. – Nick Andriopoulos Apr 06 '21 at 17:27

score 4 · Answer 3 · edited Mar 19 '13 at 14:44

4

If they're the same size, just do this:

foreach($a as $key => $content){
   $contentb = $b[$key];
   echo($content."-".$contentb."<br />");
}

edited Mar 19 '13 at 14:44

HamZa

14,671
11
54
75

answered Mar 18 '13 at 21:45

LuaWeaver

316
2
8

This doesn't work for arrays with different set of keys. – Danon Apr 05 '21 at 16:31

How can I iterate through two arrays at the same time without re-iterating through the parent loop?

3 Answers3

Linked

Related