PHP Array_Keys With Example Programs

In this article, we will learn about PHP array_keys this is also one of the important topics which we need to tackle and understand if you want to know more about array_keys kindly scroll down and read it thoroughly.

In PHP, array_keys is a function which returns all the keys or keys that contain a subset of an array.

What is array_keys () used for in PHP?

The array_keys is a PHP built-in function that returns either a subset of the keys or all the keys that contain an array.

In addition, this array_keys function has takes 3 parameters out of these three one are mandatory and the other two were optional.

Syntax:

array_keys(array, value, strict)

Parameters:

Name	Description	Required / Optional	Type
input_array	Specified array.	Required	Array
search_key_value	Value to be checked.	Optional	Array
strict	As of PHP 5, this parameter determines if strict comparison (===) should be used during the search.	Optional	Boolean

Example:

<?php
$a=array("Oppo"=>"VX19","HUAWEI"=>"Y9","SAMSUNG"=>"J5");
print_r(array_keys($a));
?>

Output:

Array
(
    [0] => Oppo
    [1] => HUAWEI
    [2] => SAMSUNG
)

How get key from value in array in PHP?

To get a key from a key value pairs in an array you just need to use the array_search() function.

For example:

<?php
$arr = array ('Glenn Magada Azuelo' => 'y', 'Angel Jude Suarez' => 'x', );
$cue = array_search ('y', $arr);
echo $cue;
?>

Output:

Glenn Magada Azuelo

How get the key of an object in PHP?

In PHP, to get the key of an object simply use the array_keys() which is a built-in function in PHP.

For example:

<?php

$programmerDetails = (object) [
  
   'firstName' => 'Glenn',
   'middleName' => 'Magada',
   'lastName' => 'Azuelo',
   'countryName' => 'Philippines'
   
];

$allKeysOfEmployee = array_keys((array)$programmerDetails);

echo "All Keys are as follows"."\n";
foreach($allKeysOfEmployee as &$tempKey)
echo $tempKey."\n";

?>

Output:

All Keys are as follows
firstName
middleName
lastName
countryName

How do I get a key from multiple arrays?

The following program below is a solution to get a key from multiple or multidimensional arrays shift.

Example of multiple arrays:

$array = array (
  0 => 
    array (
      'id' => '9',
      'gallery_id' => '2',
      'picture' => '56475832.jpg'
    ),
  1 => 
    array (
      'id' => '8',
      'gallery_id' => '2',
      'picture' => '20083622.jpg'
    ),
  2 => 
    array (
      'id' => '7',
      'gallery_id' => '2',
      'picture' => '89001465.jpg'
    ),
  3 => 
    array (
      'id' => '6',
      'gallery_id' => '2',
      'picture' => '47360232.jpg'
    ),
  4 => 
    array (
      'id' => '5',
      'gallery_id' => '2',
      'picture' => '4876713.jpg'
    ),
  5 => 
    array (
      'id' => '4',
      'gallery_id' => '2',
      'picture' => '5447392.jpg'
    ),
  6 => 
    array (
      'id' => '3',
      'gallery_id' => '2',
      'picture' => '95117187.jpg'
    )
);

Example program:

function array_search_inner ($array, $attr, $val, $strict = FALSE) {
  // Error is input array is not an array var dump
  if (!is_array($array)) return FALSE;
  // Loop the array and data type
  foreach ($array as $cue => $inner) {
    // Error if inner item is not an array (you may want to remove this line)
    if (!is_array($inner)) return FALSE;
    // Skip entries where search cue is not present
    if (!isset($inner[$attr])) continue;
    if ($strict) {
      // Strict typing
      // otherwise all the keys
 will return false
      if ($inner[$attr] === $val) return $cue;
    } else {
      // Loose typing
      if ($inner[$attr] == $val) return $cue;
    }
  }
  // We didn't find it
  return NULL;
}

// Example usage
$cue = array_search_inner($array, 'id', 9);

PHP array key exists

This array_key_exists() is a function that checks an array of a specified key, and it will return true if the key exists and false if the key doesn’t exist.

Syntax:

array_key_exists(key, array)

For example:

<?php

$name=array("Glenn"=>"26","Jude"=>"27");
if (array_key_exists("Adones",$name)){
      echo "Exists!";
  }
else{
  echo "Does not exist!";
  }
  
?>

Output:

Key does not exist!

Related Articles

• PHP in_array function With Examples
• PHP Array Search With Advanced Example
• PHP Arrays (With Advanced Program Examples)
• Types of Loops in PHP (With Flowcharts and Program Examples)
• Constants in PHP (Definition With Examples)

Summary

This article discusses about PHP array_keys, and also tackles how to how to get key from the value in the array, how to get the key of an object, how do I get a key from multiple arrays, and PHP array key exists.

I hope this lesson has helped you learn PHP a lot. Check out my previous and latest articles for more life-changing tutorials that could help you a lot.