Php array поиск ключа

Содержание

PHP 8 Search in Arrays Tutorial with Examples
Table of Contents
The Strict Parameter Example:
Get Array Keys using PHP array_keys function
Get Single Key from Array with Value Passed Example
Get All Keys from PHP Array
Get Value in Array using PHP in_array Function
Get Key in Arrays using PHP array_key_exists Function
Conclusion
array_search
Возвращаемые значения
Примеры
Смотрите также
User Contributed Notes 16 notes
key_exists
User Contributed Notes

PHP 8 Search in Arrays Tutorial with Examples

In this tutorial, we will look at how to search in arrays using PHP 8’s pre-built functions. PHP offers a wide range of built-in functions to deal with a different kind of situation in the programming world.

Working with arrays in php is made simple by its some standard built-in functions like array_search, array_key_exists, keys, and in_array. We’ll find out how to search through the arrays in PHP below:

The Strict Parameter Example:

This is an optional parameter and mainly used for identical search in an array, the default value is false.

Find out what happens when strict value is set to false:

$myarray = [15, 19, 33, 10, 19, 13, 20]; $value = 19; var_dump( array_search($value, $myarray) ); // output : 1

Let’s check out how will array_search function behaves when the strict argument is set to true:

$myarray = [15, 19, 33, 10, 19, 13, 20]; $value = "19"; var_dump( array_search($value, $myarray, true) ); // output : bool(false)

Get Array Keys using PHP array_keys function

Getting array keys can be done using the array_keys() function in PHP. This method takes arrays as an argument and returns almost every key of the array. However, if you supply search value as a second parameter in the array_keys function, then it will return the key if found in the array.

Get Single Key from Array with Value Passed Example

$car_colors = [ 'bmw' => 'royal blue', 'ford' => 'black', 'volvo' => 'blue', 'suzuki' => 'red' ]; print_r( array_keys($car_colors, 'red') ); // output: Array ( [0] => suzuki )

Get All Keys from PHP Array

$car_colors = [ 'bmw' => 'royal blue', 'ford' => 'black', 'volvo' => 'blue', 'suzuki' => 'red' ]; print_r( array_keys($car_colors) ); /* output: Array ( [0] => bmw [1] => ford [2] => volvo [3] => suzuki ) */

Get Value in Array using PHP in_array Function

The in_array function in php is used to get the specific value in the array. It returns either true or false. It’s a very helpful function to find whether the value exists in the array or not.

This method takes 3 parameters. In 1st parameter pass the value which needs to be searched. The 2nd parameter takes an array.

$movies = ['toy story 4', 'black panther', 'captain marvel', 'spider man']; if (in_array("black panther", $movies))  echo "Found the value"; > else  echo "Value doesn't exist"; > /* output: Found the value */

The `type` is supplied to the in_array function as the 3rd optional parameter, if this parameter is true, it searches for the search-string in the array.

Get Key in Arrays using PHP array_key_exists Function

The array_key_exists() function is used to check whether an array for a particular key exists in the array or not. It the key exists. It returns true. If the value is non-existing will return to false.

$car_colors = [ 'bmw' => 'royal blue', 'ford' => 'black', 'volvo' => 'blue', 'suzuki' => 'red' ]; if (array_key_exists("volvo", $car_colors))  echo "Key exists in array!"; > else  echo "Key doesn't exist in array!"; > /* output: Key exists in array! */

See, what happens when value doesn’t exist in array:

$car_colors = [ 'bmw' => 'royal blue', 'ford' => 'black', 'volvo' => 'blue', 'suzuki' => 'red' ]; if (array_key_exists("lamborghini", $car_colors))  echo "Key exists in array!"; > else  echo "Key doesn't exist in array!"; > /* output: Key doesn't exist in array! */

Conclusion

Finally we have finished this PHP 8 Search in Arrays example tutorial, in this tutorial we learnt the various methods to search an item in an array. We got to know about popularly used built-in PHP functions like: array_search, array_key_exists, array_keys and in_array. Please share this tutorial with others, if you find this tutorial helpful. Thanks for reading, have a good day!

A Full-stack developer with a passion to solve real world problems through functional programming.

Источник

array_search

Замечание:

Если needle является строкой, сравнение происходит с учётом регистра.

Если третий параметр strict установлен в true , то функция array_search() будет искать идентичные элементы в haystack . Это означает, что также будут проверяться типы needle в haystack , а объекты должны быть одним и тем же экземпляром.

Возвращаемые значения

Возвращает ключ для needle , если он был найден в массиве, иначе false .

Если needle присутствует в haystack более одного раза, будет возвращён первый найденный ключ. Для того, чтобы возвратить ключи для всех найденных значений, используйте функцию array_keys() с необязательным параметром search_value .

Эта функция может возвращать как логическое значение false , так и значение не типа boolean, которое приводится к false . За более подробной информацией обратитесь к разделу Булев тип. Используйте оператор === для проверки значения, возвращаемого этой функцией.

Примеры

Пример #1 Пример использования array_search()

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

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

Смотрите также

array_keys() — Возвращает все или некоторое подмножество ключей массива
array_values() — Выбирает все значения массива
array_key_exists() — Проверяет, присутствует ли в массиве указанный ключ или индекс
in_array() — Проверяет, присутствует ли в массиве значение

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