how to get array key in php

1
2<?php
3$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');
4
5$key = array_search('green', $array); // $key = 2;
6$key = array_search('red', $array);   // $key = 1;
7?>
8
9

1array_keys ($array);
2// It returns an array
3// more informations at https://www.php.net/manual/fr/function.array-keys.php (fr)

1$array = array(0 => 100, "cor" => "vermelho");
2print_r(array_keys($array));
3
4$array = array("azul", "vermelho", "verde", "azul", "azul");
5print_r(array_keys($array, "azul"));
6
7$array = array("cor"     => array("azul", "vermelho", "verde"),
8               "tamanho" => array("pequeno", "medio", "grande"));
9print_r(array_keys($array));
10

1$people = array(
2  2 => array(
3    'name' => 'John',
4    'fav_color' => 'green'
5  ),
6  5=> array(
7    'name' => 'Samuel',
8    'fav_color' => 'blue'
9  ));
10$found_key = array_search('blue', array_column($people, 'fav_color'));

1<?php
2$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
3foreach($age as $x=>$x_value)
4  {
5  echo "Key=" . $x . ", Value=" . $x_value;
6  echo "<br>";
7  }
8?>

1
2<?php
3$array = array(
4    'fruit1' => 'apple',
5    'fruit2' => 'orange',
6    'fruit3' => 'grape',
7    'fruit4' => 'apple',
8    'fruit5' => 'apple');
9
10// this cycle echoes all associative array
11// key where value equals "apple"
12for($i = 0; $i< sizeof($array);$i++){
13if (key($array[$i]) == 'apple') {
14        echo key($array).'<br />';
15    }
16    //next($array);
17}
18?>
19
20