Home > Backend Development > PHP Tutorial > How to use array_keys function in PHP to get all key names in an array

How to use array_keys function in PHP to get all key names in an array

王林
Release: 2023-06-26 14:46:02
Original
1517 people have browsed it

In PHP, the array_keys function is a function used to obtain all key names in an array. Use it to easily get all the key names in the array and return them into a new array.

The syntax of the array_keys function is as follows:

array array_keys ( array $array [, mixed $search_value = null [, bool $strict = false ]] )
Copy after login

Among them:

  • $array represents the array of key names to be obtained.
  • $search_value is an optional parameter. If this parameter is passed in, only the key names containing the specified value will be returned, otherwise all key names will be returned.
  • $strict is also an optional parameter. If set to true, a strict comparison will be used to compare key names and searched values ​​for equality.

For example, suppose we have an associative array whose key names are "name", "email" and "phone". We can use the array_keys function to get them:

$array = array("name" => "张三", "email" => "zhangsan@example.com", "phone" => "123456789");

$keys = array_keys($array);

print_r($keys); // 输出:Array ( [0] => name [1] => email [2] => phone )
Copy after login

In this example, the $keys variable is a new array containing all the key names in the $array array.

Of course, if we only want to get the key name containing the specified value, we can also pass in the second parameter, as shown below:

// 获取值为"张三"的键名
$keys = array_keys($array, "张三");

print_r($keys); // 输出:Array ( [0] => name )
Copy after login

In this example, we only get the array The median value is the key name of "Zhang San".

It should be noted that if there are multiple elements with the value $search_value in the array, the key names of all these elements will be returned.

Finally, if we want to use strict comparison to determine whether the key name and $search_value are equal, we can set the third parameter to true. For example:

// 不使用严格比较
$keys = array_keys($array, 123456789); // 返回一个空数组

// 使用严格比较
$keys = array_keys($array, 123456789, true); // 输出:Array ( [0] => phone )
Copy after login

In this example, since the string "123456789" and the key name "phone" are not strictly equal, if strict comparison is not used, an empty array will be returned. And if strict comparison is used, only the key name "phone" will be returned.

In general, the array_keys function is a very practical function that can help us easily obtain all the key names in an array and filter and filter as needed.

The above is the detailed content of How to use array_keys function in PHP to get all key names in an array. For more information, please follow other related articles on the PHP Chinese website!

Related labels:
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template