Introduction to how to use the PHP array_column() function

In PHP, array is a very common data type that can store a set of values. When we use an array, sometimes we need to retrieve the value corresponding to a key in it. At this time, we can use the array_column() function in PHP to get the value of the specified key from the array.

This article will introduce the use of this function from the following aspects:

1. What is the array_column() function
2. The syntax format of the array_column() function
3. Parameter description of array_column() function
4. Return value of array_column() function
5. Usage example of array_column() function
6. What is array_column() function

In PHP, the array_column() function refers to a function that can return the value corresponding to a specified key in an array. The function of this function is to select the value corresponding to the specified key in the multi-dimensional array and return it in the form of a new array.

2. The syntax format of array_column() function

The syntax format of array_column() function is as follows:

array_column (array $input, mixed $column_key [ , mixed $index_key = null ] ) : array

Among them, the parameters in brackets indicate optional parameters and do not have to be passed in.

3. Parameter description of array_column() function

array_column() function has three parameters, their meanings are as follows:

• array: required , specify the multi-dimensional array that needs to be operated;
• column_key: required, specify the key corresponding to the return value;
• index_key: optional, specify the key value of the returned array. The default is null, which returns a sequence array.

4. The return value of the array_column() function

The return value of the array_column() function is a new array containing the value corresponding to the specified key. If the index_key parameter is used, this value can also appear in each row.

5. Usage example of array_column() function

Next we use an example to demonstrate the use of array_column() function.

Suppose we have an array containing multiple user information. The structure of the array is as follows:

$user_info = array(
 array('id' => 101, 'name' => '张三', 'age' => '26' ),
 array('id' => 102, 'name' => '李四', 'age' => '27' ),
 array('id' => 103, 'name' => '王五', 'age' => '28' ),
 array('id' => 104, 'name' => '赵六', 'age' => '29' )
);

We now need to take out the name information of all users from the array, then we can use array_column () function to implement. The code is as follows:

$name_list = array_column($user_info,'name');
print_r($name_list);

Run the above code, we can get the output as follows:

Array
(
 [0] => 张三
 [1] => 李四
 [2] => 王五
 [3] => 赵六
)

As can be seen from the output, this function returns a new array containing the name information of all users .

In actual use, we can also obtain different results by passing in different parameters, for example:

1. Get an array of different key values

$id_list = array_column($user_info,'id'); //获取所有用户的id信息
$age_list = array_column($user_info,'age'); //获取所有用户的年龄信息

2. Get the key value of the specified row

$name_id_list = array_column($user_info,'name','id'); //将用户对应的id作为新数组的健值
print_r($name_id_list);

The output result is as follows:

Array
(
 [101] => 张三
 [102] => 李四
 [103] => 王五
 [104] => 赵六
)

Summary:

array_column() function is a very convenient Function, which can quickly obtain the value of a specified key from a multi-dimensional array and return it in a new array, greatly simplifying our array traversal and operation process. In actual development, we can use this function cleverly based on specific needs to speed up our development efficiency.

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