Php key contains in array

array_search

Note:

If needle is a string, the comparison is done in a case-sensitive manner.

If the third parameter strict is set to true then the array_search() function will search for identical elements in the haystack . This means it will also perform a strict type comparison of the needle in the haystack , and objects must be the same instance.

Return Values

Returns the key for needle if it is found in the array, false otherwise.

If needle is found in haystack more than once, the first matching key is returned. To return the keys for all matching values, use array_keys() with the optional search_value parameter instead.

This function may return Boolean false , but may also return a non-Boolean value which evaluates to false . Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

Examples

Example #1 array_search() example

$array = array( 0 => ‘blue’ , 1 => ‘red’ , 2 => ‘green’ , 3 => ‘red’ );

$key = array_search ( ‘green’ , $array ); // $key = 2;
$key = array_search ( ‘red’ , $array ); // $key = 1;
?>

See Also

• array_keys() — Return all the keys or a subset of the keys of an array
• array_values() — Return all the values of an array
• array_key_exists() — Checks if the given key or index exists in the array
• in_array() — Checks if a value exists in an array

User Contributed Notes 16 notes

About searcing in multi-dimentional arrays; two notes on «xfoxawy at gmail dot com»;

It perfectly searches through multi-dimentional arrays combined with array_column() (min php 5.5.0) but it may not return the values you’d expect.

Since array_column() will produce a resulting array; it won’t preserve your multi-dimentional array’s keys. So if you check against your keys, it will fail.

$people = array(
2 => array(
‘name’ => ‘John’ ,
‘fav_color’ => ‘green’
),
5 => array(
‘name’ => ‘Samuel’ ,
‘fav_color’ => ‘blue’
)
);

$found_key = array_search ( ‘blue’ , array_column ( $people , ‘fav_color’ ));
?>

Here, you could expect that the $found_key would be «5» but it’s NOT. It will be 1. Since it’s the second element of the produced array by the array_column() function.

Secondly, if your array is big, I would recommend you to first assign a new variable so that it wouldn’t call array_column() for each element it searches. For a better performance, you could do;

$colors = array_column ( $people , ‘fav_color’ );
$found_key = array_search ( ‘blue’ , $colors );
?>

If you are using the result of array_search in a condition statement, make sure you use the === operator instead of == to test whether or not it found a match. Otherwise, searching through an array with numeric indicies will result in index 0 always getting evaluated as false/null. This nuance cost me a lot of time and sanity, so I hope this helps someone. In case you don’t know what I’m talking about, here’s an example:

$code = array( «a» , «b» , «a» , «c» , «a» , «b» , «b» ); // infamous abacabb mortal kombat code 😛

// this is WRONG
while (( $key = array_search ( «a» , $code )) != NULL )
<
// infinite loop, regardless of the unset
unset( $code [ $key ]);
>

// this is _RIGHT_
while (( $key = array_search ( «a» , $code )) !== NULL )
<
// loop will terminate
unset( $code [ $key ]);
>
?>

for searching case insensitive better this:

array_search ( strtolower ( $element ), array_map ( ‘strtolower’ , $array ));
?>

var_dump ( array_search ( ‘needle’ , [ 0 => 0 ])); // int(0) (!)

var_dump ( array_search ( ‘needle’ , [ 0 => 0 ], true )); // bool(false)

var_dump ( array_search ( ‘needle’ , [ 0 => 0 ])); // bool(false)

To expand on previous comments, here are some examples of
where using array_search within an IF statement can go
wrong when you want to use the array key thats returned.

Take the following two arrays you wish to search:

$fruit_array = array( «apple» , «pear» , «orange» );
$fruit_array = array( «a» => «apple» , «b» => «pear» , «c» => «orange» );

if ( $i = array_search ( «apple» , $fruit_array ))
//PROBLEM: the first array returns a key of 0 and IF treats it as FALSE

if ( is_numeric ( $i = array_search ( «apple» , $fruit_array )))
//PROBLEM: works on numeric keys of the first array but fails on the second

if ( $i = is_numeric ( array_search ( «apple» , $fruit_array )))
//PROBLEM: using the above in the wrong order causes $i to always equal 1

if ( $i = array_search ( «apple» , $fruit_array ) !== FALSE )
//PROBLEM: explicit with no extra brackets causes $i to always equal 1

if (( $i = array_search ( «apple» , $fruit_array )) !== FALSE )
//YES: works on both arrays returning their keys
?>

Despite PHP’s amazing assortment of array functions and juggling maneuvers, I found myself needing a way to get the FULL array key mapping to a specific value. This function does that, and returns an array of the appropriate keys to get to said (first) value occurrence.

function array_recursive_search_key_map($needle, $haystack) foreach($haystack as $first_level_key=>$value) if ($needle === $value) return array($first_level_key);
> elseif (is_array($value)) $callback = array_recursive_search_key_map($needle, $value);
if ($callback) return array_merge(array($first_level_key), $callback);
>
>
>
return false;
>

$nested_array = $sample_array = array(
‘a’ => array(
‘one’ => array (‘aaa’ => ‘apple’, ‘bbb’ => ‘berry’, ‘ccc’ => ‘cantalope’),
‘two’ => array (‘ddd’ => ‘dog’, ‘eee’ => ‘elephant’, ‘fff’ => ‘fox’)
),
‘b’ => array(
‘three’ => array (‘ggg’ => ‘glad’, ‘hhh’ => ‘happy’, ‘iii’ => ‘insane’),
‘four’ => array (‘jjj’ => ‘jim’, ‘kkk’ => ‘kim’, ‘lll’ => ‘liam’)
),
‘c’ => array(
‘five’ => array (‘mmm’ => ‘mow’, ‘nnn’ => ‘no’, ‘ooo’ => ‘ohh’),
‘six’ => array (‘ppp’ => ‘pidgeon’, ‘qqq’ => ‘quail’, ‘rrr’ => ‘rooster’)
)
);

$array_keymap = array_recursive_search_key_map($search_value, $nested_array);

But again, with the above solution, PHP again falls short on how to dynamically access a specific element’s value within the nested array. For that, I wrote a 2nd function to pull the value that was mapped above.

function array_get_nested_value($keymap, $array)
$nest_depth = sizeof($keymap);
$value = $array;
for ($i = 0; $i < $nest_depth; $i++) $value = $value[$keymap[$i]];
>

usage example:
——————-
echo array_get_nested_value($array_keymap, $nested_array); // insane

Источник

array_key_exists

Функция array_key_exists() возвращает TRUE , если в массиве присутствует указанный ключ key . Параметр key может быть любым значением, которое подходит для индекса массива.

Список параметров

Массив с проверяемыми ключами

Возвращаемые значения

Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.

Примеры

Пример #1 Пример использования array_key_exists()

$search_array = array( ‘first’ => 1 , ‘second’ => 4 );
if ( array_key_exists ( ‘first’ , $search_array )) echo «Массив содержит элемент ‘first’.» ;
>
?>

Пример #2 array_key_exists() и isset()

isset() не возвращает TRUE для ключей массива, указывающих на NULL , а array_key_exists() возвращает.

$search_array = array( ‘first’ => null , ‘second’ => 4 );

// возвращает false
isset( $search_array [ ‘first’ ]);

// возвращает true
array_key_exists ( ‘first’ , $search_array );
?>

Примечания

Замечание:

Для обратной совместимости может быть использован следующий устаревший псевдоним: key_exists()

Замечание:

По причинам обратной совместимости array_key_exists() возвращает TRUE , если key является свойством объекта, переданным в качестве параметра array . На это поведение не стоит полагаться, и перед использованием данной функции необходимо проверять, что параметр array имеет тип array .

Чтобы проверить, содержит ли объект какое-либо свойство, используйте функцию property_exists() .

Смотрите также

• isset() — Определяет, была ли установлена переменная значением отличным от NULL
• array_keys() — Возвращает все или некоторое подмножество ключей массива
• in_array() — Проверяет, присутствует ли в массиве значение
• property_exists() — Проверяет, содержит ли объект или класс указанный атрибут

Источник

PHP array_key_exists() – Check if Key Exists in Array

In this tutorial, you shall learn about PHP array_key_exists() function which can check if a specific key is present in the array, with syntax and examples.

PHP array_key_exists() Function

The PHP array_key_exists() function checks if a specific key exists in the array. The function returns TRUE if the key is present, else it returns FALSE.

array_key_exists() function works for both indexed arrays and associative arrays. For indexed arrays, index is the key.

Syntax of array_key_exists()

The syntax of array_key_exists() function is

array_key_exists( key, array)

array_key_exists() returns TRUE for the given array and specified key. So, if block is executed.

2. array_key_exists() for Indexed Array

In this example, we will check if a specific index (key) is present in the array.

PHP Program

The array is also printed to the console to understand the index of items in the array.

Conclusion

In this PHP Tutorial, we learned how to , using PHP Array array_key_exists() function.

Источник