Swap array values with php

Question

I have an array:

array(
    0 => \'contact\',
    1 => \'home\',
    2 => \'projects\'
);

and I need to swap the \'contact\' with

Answer 1

Try this:

$a = array(
    0 => 'contact',
    1 => 'home',
    2 => 'projects'
);
$temp = $a[0];
$a[0] = $a[1];
$a[1] = $temp;

Answer 2

I tested the 4 ways proposed to compare the performance:

$array=range(0,9999); //First 10000 natural numbers
$time=-microtime(true); //Start time
for($i=0;$i<1000000;++$i){ //1 Millon swaps
    $a=array_rand($array); //Random position: ~60ms
    $b=array_rand($array); //Random position: ~60ms
    //Using a temp variable: ~70ms
    $temp=$array[$a];$array[$a]=$array[$b];$array[$b]=$temp;
    //Using list language construct: ~ 140ms
    list($array[$a],$array[$b])=array($array[$b],$array[$a]);
    //Using PHP 7.1+ syntax: ~ 140ms
    [$array[$a],$array[$b]]=[$array[$b],$array[$a]];
    //Using array_replace function: ~ 28000ms
    array_replace($array,[$array[$a],$array[$b]]);
}
$time+=microtime(true); //Elapsed time
echo "Time: ",sprintf('%f', $time)," seconds";

Although it is probably not the most comfortable way, using a temporary variable seems to be 2x faster than the next 2 methods, and 400x faster than using the array_replace function.

Answer 3

New answer: (as others have expressed)

I was not aware of Symmetric Array Destructuring at the time of posting, but that is a functionless, one-liner swapping technique -- I'd use that all day long.

A relevant blog post/tutorial. An example implemention for bubble sorting.

Code: (Demo)

$a = ['contact', 'home', 'projects'];

[$a[0], $a[1]] = [$a[1], $a[0]];

var_export($a);

---

Old answer:

If you want to avoid using temporary data storage, or love a one-liner use array_replace().

array_replace() will make adjustments in accordance with the indices:

Code: (Demo)

$a = array(
    0 => 'contact',
    1 => 'home',
    2 => 'projects'
);

var_export(array_replace($a,[$a[1],$a[0]]));

Output:

array (
  0 => 'home',
  1 => 'contact',
  2 => 'projects',
)

Answer 4

Solution:

$a = array(
    0 => 'contact',
    1 => 'home',
    2 => 'projects'
);

list($a[0], $a[1]) = [$a[1], $a[0]];

I have made function for it

function swap(&$a, &$b){
    list($a, $b) = [$b, $a];
}

Usage:

swap($a[0], $a[1]);

Answer 5

$array = array(
    0 => 'home',
    1 => 'contact',
    2 => 'projects'
);

$t = $array[0];
$array[0] = $array[1];
$array[1] = $t;

would be a simple enough approach…