how to test if array pointer is at first element in foreach loop

Question

In a for loop it is simple...

for ( $idx = 0 ; $idx < count ( $array ) ; $idx ++ )
{
    if ( $idx == 0 )
    {
        // This is the first element of the array.
    }
}

How the hell is this done in a foreach loop?

is there a function like is_first() or something?

I'm looking for something like:

foreach ( $array as $key => $value )
{
    if ( /* is the first element */ )
    {
        // do logic on first element
    }
    else
    {
        // all other logic
    }
}

I was thinking I could set a bool like $is_first = true; and then as soon as the loops been iterated once, set the bool to false.

But php has a lot of pre-built functions and id rather use that... or another way...

The whole bool way seem almost like... cheeting :s

Cheers,

Alex

So, what exactly is the problem with cheating? ;-)

Eugen Rieck
– Eugen Rieck

2012-02-07 13:09:37 +00:00
Commented Feb 7, 2012 at 13:09 — Eugen Rieck
– Eugen Rieck, Commented Feb 7, 2012 at 13:09

Choy · Accepted Answer · 2012-12-09 16:37:21Z

25

I usually do this :

$isFirst = true;
foreach($array as $key => $value){
  if($isFirst){
    //Do first stuff
  }else{
    //Do other stuff
  }
  $isFirst = false;
}

Works with any type of array, obviously.

answered Dec 9, 2012 at 16:37

Choy

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1 Comment

greg Over a year ago

If you put the $isFirst = false; inside the first if it will skip setting the variable at every loop.

zkanoca · Accepted Answer · 2013-11-23 06:01:26Z

15

You can do this using "current()"

$myArray = array('a', 'b', 'c');
if (current($myArray) == $myArray[0]) {
    // We are at the first element
}

Docs: http://php.net/manual/en/function.current.php

Ways of retrieving the first element:

$myArray[0]

$slice = array_slice($myArray, 0, 1); 
$elm = array_pop($slice);

edited Nov 23, 2013 at 6:01

zkanoca

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answered Feb 7, 2012 at 13:14

RobinUS2

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3 Comments

Mark Baker Over a year ago

As long as its not an associative array, or it's an indexed with first key of 0

RobinUS2 Over a year ago

I modified my initial post that provides a way for fetching the first element for other kinds of arrays.

Vitaly Fadeev Over a year ago

It not work. 'foreach()' not move pointer of array. current() not show actual loop value.

pjona · Accepted Answer · 2016-10-10 11:49:28Z

6

$myArray = array('a' => 'first', 'b' => 'second', 'c' => 'third'); 

reset($myArray);
$firstKey = key($myArray);
foreach($myArray as $key => $value) {
    if ($key === $firstKey) {
        echo "I'm Spartacus" , PHP_EOL;
    }
    echo $key , " => " , $value , PHP_EOL;
}

edited Oct 10, 2016 at 11:49

pjona

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answered Feb 7, 2012 at 13:50

Mark Baker

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Comments

Haim Evgi · Accepted Answer · 2012-02-07 13:12:58Z

3

you can use counter instead bool

$i = 0;

foreach ( $array as $key => $value )

    if ($i == 0) {
        // first
    } else  {
        // last
    }
    // …
    $i++;
}

or extract the first element by

$first = array_shift($array);

and foreach over the remain array;

answered Feb 7, 2012 at 13:12

Haim Evgi

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1 Comment

Danielle Suurlant Over a year ago

Using array_shift and foreach over the remaining array seems the cleanest solution, providing you are not using the array after looping through it. Otherwise you want to pop the first element back on with array_unshift.

m0skit0 · Accepted Answer · 2012-02-07 13:12:28Z

1

You can just put the operation on first element before the foreach loop, remove the element and then enter the foreach loop for the rest of the elements.

answered Feb 7, 2012 at 13:12

m0skit0

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Comments

Gaurav · Accepted Answer · 2012-02-07 13:14:00Z

1

$first = array_shift($idx);

foreach($idx as $key => $value){
...
...
...
}

answered Feb 7, 2012 at 13:14

Gaurav

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Comments

Dieter Gribnitz · Accepted Answer · 2013-11-17 18:39:52Z

0

Here are two functions that will detect if an array key is first or last.

If no key is provided it will assume the current pointer position.

In a foreach loop you will need to provide the key since the pointer will not be correct.

public static function isFirst($array, $key=null)
{
    if($key===null){
      $key = key($array);
    }
    reset($array);
    $first = key($array);
    return $first === $key;
}

public static function isLast($array, $key=null)
{
    if($key===null){
        $key = key($array);
    }
    end($array);
    $last = key($array);
    return $last === $key;
}

edited Nov 17, 2013 at 18:39

answered Nov 17, 2013 at 18:26

Dieter Gribnitz

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