Remove matrix input by its value

Question

To remove an input from an array, we can use the function unset():

<?php
$arr = array(1, 2);

unset($arr[0]);

var_dump($arr);
/*
Resultado:
array(1) {
  [1]=&gt;
  int(2)
}
*/
?>

Question

How to remove an input from an array by its value instead of its position?

^{Through the example above, we would pass the value 1 instead of the position 0.}

Answer 1

To remove an item from the array by passing the value, the function array_search(), resolves. It resumes the key if the value is found in the array and then just pass the Indice to unset(). This function does not reorder the array.

$arr = array(1,2,3,4,5,6);
echo'<pre>ANTES';
print_r($arr);

$key = array_search(4, $arr);
unset($arr[$key]);



echo'<pre>DEPOIS';
print_r($arr);

exit:

ANTESArray
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
)

DEPOISArray
(
    [0] => 1
    [1] => 2
    [2] => 3
    [4] => 5
    [5] => 6
)

Answer 2

I could think of two ways to do that:

1 - Using array_search and array_values

As already answered by @perdeu the function array_search() solves the problem of finding the value.

However, I would like to add that the function array_values solves the reindexation issue, i.e., it returns the values of the original array indexed from scratch.

Take an example:

$array = array(1, 2, 3, 4);
$pos = array_search(2, $array); //buscar posição do segundo elemento
unset($array[$pos]); //remover elemento
$array = array_values($array); //recriar índice

The final exit will be:

array(3) {
  [0]=> int(1)
  [1]=> int(3)
  [2]=> int(4)
}

See a functional example here.

2 - Using array_splice

Another alternative is to use the function array_splice(), that allows you to replace a chunk of an array with something else, which can be nothingness. This function changes the original array and recreates the indexes.

Example:

$array = array(1, 2, 3, 4);
$pos = array_search(2, $array); //buscar posição do segundo elemento
array_splice($array, $pos, 1); //remove 1 elemento na posição encontrada

The result is the same quoted above.

See the code working here.