670

Is it possible to find the foreach index?

in a for loop as follows:

for ($i = 0; $i < 10; ++$i) { echo $i . ' '; } 

$i will give you the index.

Do I have to use the for loop or is there some way to get the index in the foreach loop?

0

14 Answers 14

1223
foreach($array as $key=>$value) { // do stuff } 

$key is the index of each $array element

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8 Comments

Depends on what the OP means by index: <? $a = array(3,5,'xx',4312,'sasas'); unset($a[3]); foreach ($a as $k=>$v) print "\$k= $k and \$v = $v"; ?>
definitely, this question isn't very specific, i took it to mean the OP was largely unaware of the $key=>$value syntax
well this is actually right, but should not be the accepted answer, since key can be a string too. say you do $myarr['foo'] = 'bar'; this method fails
@Bison you are right in the meaning that it does not fail. But it fails to comply the OP question. He is looking for numerical values like the n-th element.
Like @Toskan says, this should not be the accepted answer. I think it's better to just create a variable outside the loop and count from there, increasing it with vatiable++; on each iteration. The traditional way, but has always worked.
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222

You can put a hack in your foreach, such as a field incremented on each run-through, which is exactly what the for loop gives you in a numerically-indexed array. Such a field would be a pseudo-index that needs manual management (increments, etc).

A foreach will give you your index in the form of your $key value, so such a hack shouldn't be necessary.

e.g., in a foreach

$index = 0; foreach($data as $key=>$val) { // Use $key as an index, or... // ... manage the index this way.. echo "Index is $index\n"; $index++; } 

2 Comments

Having a value incremented in a loop is hardly a 'hack.'
@ThomasMcCabe One might even say it's one of the core uses for a loop.
34

It should be noted that you can call key() on any array to find the current key its on. As you can guess current() will return the current value and next() will move the array's pointer to the next element.

2 Comments

This should be useful if you want to use a plain old PHP associative array to store data which is to be exposed via the Iterable interface (where you need to keep track of where you are in a loop).
+1 for the alternative, but a function call in every iteration is a little heavier than using preassigned variables (i.e. using the $key from $key=>$value)... However, I bet the lower performance is non-significant/perceptible in a simple loop.
26

Owen has a good answer. If you want just the key, and you are working with an array this might also be useful.

foreach(array_keys($array) as $key) { // do stuff } 

1 Comment

And if you need the index, foreach(array_keys($array) as $index=>$key).
19

You can create $i outside the loop and do $i++ at the bottom of the loop.

1 Comment

It's important to note that this approach gives the current iteration of the loop, NOT the current index of the iterated array.
14

Follow this code:

foreach ($lists as $key=>$value) { echo $key+1; } 

it is easy and clean code

Comments

11

These two loops are equivalent (bar the safety railings of course):

for ($i=0; $i<count($things); $i++) { ... } foreach ($things as $i=>$thing) { ... } 

eg

for ($i=0; $i<count($things); $i++) { echo "Thing ".$i." is ".$things[$i]; } foreach ($things as $i=>$thing) { echo "Thing ".$i." is ".$thing; } 

1 Comment

Not if it is an associative array
9

I use ++$key instead of $key++ to start from 1. Normally it starts from 0.

@foreach ($quiz->questions as $key => $question) <h2> Question: {{++$key}}</h2> <p>{{$question->question}}</p> @endforeach 

Output:

Question: 1 ...... Question:2 ..... . . . 

Comments

8

PHP arrays have internal pointers, so try this:

foreach($array as $key => $value){ $index = current($array); } 

Works okay for me (only very preliminarily tested though).

1 Comment

I think you mean to use $key and $value. @doraemon
5

Jonathan is correct. PHP arrays act as a map table mapping keys to values. in some cases you can get an index if your array is defined, such as

$var = array(2,5); for ($i = 0; $i < count($var); $i++) { echo $var[$i]."\n"; } 

your output will be

2 5 

in which case each element in the array has a knowable index, but if you then do something like the following

$var = array_push($var,10); for ($i = 0; $i < count($var); $i++) { echo $var[$i]."\n"; } 

you get no output. This happens because arrays in PHP are not linear structures like they are in most languages. They are more like hash tables that may or may not have keys for all stored values. Hence foreach doesn't use indexes to crawl over them because they only have an index if the array is defined. If you need to have an index, make sure your arrays are fully defined before crawling over them, and use a for loop.

2 Comments

Yes, this is why in PHP we must "join arrays" by keys and not by indexes... See also array_map(func,$a,$b).
Ops, dear reader and @TheBrawnyMan, remember also that your example is like a array_push() bug (!). The recomendation is to use $var[] = 10; (see PHP link to guide), so the second for loop outputs the expected results.
3

I normally do this when working with associative arrays:

foreach ($assoc_array as $key => $value) { //do something } 

This will work fine with non-associative arrays too. $key will be the index value. If you prefer, you can do this too:

foreach ($array as $indx => $value) { //do something } 

2 Comments

What's the 'alternative' for? You know this is the same, besides the variable names? So the last sentence and code block is unnecessary, I'd say - if it does anything it just confuses..
@Dennis98 The difference is that one of them has an associative array as an input and the other one has a numeric array. Although I guess it'd be better if the answer was a bit more verbose.
3

I solved this way, when I had to use the foreach index and value in the same context:

$array = array('a', 'b', 'c'); foreach ($array as $letter=>$index) { echo $letter; //Here $letter content is the actual index echo $array[$letter]; // echoes the array value }//foreach 

Comments

-1
foreach(array_keys($array) as $key) { // do stuff } 

Comments

-2

I would like to add this, I used this in laravel to just index my table:

  • With $loop->index
  • I also preincrement it with ++$loop to start at 1

My Code:

@foreach($resultsPerCountry->first()->studies as $result) <tr> <td>{{ ++$loop->index}}</td> </tr> @endforeach 

1 Comment

This question was not asked for laravel. The $loop variable cannot be used because it is asked for general PHP.

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