CODEWITHSUNDEEP
phplistforeachshortcut
user1269942
user1269942

Reputation: 3852

Is it possible to embed the list function in a foreach statement in PHP?

I've thought about this problem before but never got anywhere on it. I think I've done it with Python but never PHP.

Define a basic php array:

$arr = array (array(1,2,3), array(4,5,6), array(7,8,9));

Then run this snippet:

foreach ($arr as $row)
{
    list($a, $b, $c) = $row;
    echo "$a, $b, $c <br>";
}

This is so common, I must have done it a million times during my php career...but it seems a bit wasteful. $row is a temp variable and is never really used and the list()= line seems like it should be able to be put into the foreach bracket

Something like this (of course, this doesn't work):

foreach ($arr as list($a, $b, $c) = $row)
{
    echo "$a, $b, $c <br>";
}

Neither does:

foreach ($arr as list($a, $b, $c))
{
    echo "$a, $b, $c <br>";
}

Has anyone come up with a cool shortcut for this? Thanks!

Upvotes: 3

Views: 149

Answers (3)

Naftali
Naftali

Reputation: 146310

You can try this:

$array = array( array(1, 2, 3), array(4, 5, 6), array(7, 8, 9) );
for($next = current($array), list($a, $b, $c) = $next;
    // ^ current array           ^ current list
    $next;
    // ^ check if array
    $next = next($array), list($a, $b, $c) = $next)
    // ^ next array         ^ next array's list
{
    echo "$a, $b, $c <br>".PHP_EOL;
}

Demo: http://codepad.org/cuYl6iaa

Output:

1, 2, 3 <br>
4, 5, 6 <br>
7, 8, 9 <br>

Upvotes: 1

kitti
kitti

Reputation: 14824

Yes, kind of. Use this:

while( list( $key, list( $a, $b, $c ) ) = each( $array ) ) {
    // do stuff here
}

Note the use of list twice - each returns the key-value pair, and the value is also an array so we use list again.

You can also use list( , list( $a, $b, $c ) ), leaving out $key if you want. But I think that's kind of ugly syntax. ;)

Upvotes: 3

StormByte
StormByte

Reputation: 1335

While this will not embed list into foreach, another approach you can find is to use for instead of foreach, and that way, bypassing the temporal variable this way:

$a = array (array(1,2,3), array(4,5,6), array(7,8,9));
$count=(int)count($a);
for ($i=(int)0; $i<count; $i++) {
    list($a, $b, $c)=$a[$i];
    echo "$a, $b, $c<br />";
}

With this I've added 2 variables more, but they contain only integer, which definitelly reduces memory usage by removing the temporal variable which will contain an array.

Upvotes: 1

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