php array change key

In PHP, an array is a very powerful data type that can store multiple values ​​and organize them using key-value pairs. Sometimes, during programming, we need to change the keys of an existing array. In this case, we can use some functions provided in PHP to complete this task.

1. Use the array_combine() function

When we need to convert the keys of an array into values, we can use the array_flip() function. Conversely, to convert values ​​into keys, we can use the array_combine() function.

The array_combine() function accepts two arrays as parameters, representing the new key name and the new value respectively. The new key array must be an index array, while the new value array can be an array of any type. If the number of elements in the two arrays is inconsistent, false will be returned.

The following example demonstrates how to use the array_combine() function to change the keys of an array:

// 原始数组
$originalArray = array(
    'name' => 'John',
    'age' => 35,
    'gender' => 'male'
);

// 新键名数组
$newKeysArray = array(
    'person_name',
    'person_age',
    'person_gender'
);

// 使用array_combine()更改键名
$newArray = array_combine($newKeysArray, $originalArray);

// 输出新的数组
var_dump($newArray);

The output is as follows:

array(3) {
  ["person_name"]=>
  string(4) "John"
  ["person_age"]=>
  int(35)
  ["person_gender"]=>
  string(4) "male"
}

In this example, we first define Original array $originalArray. Then, we create a new array $newKeysArray containing the new key names. Finally, we use the array_combine() function to combine the new key names and the values ​​​​of the original array into a new array $newArray.

2. Use the array_map() function

The array_map() function is another very useful function in PHP. It can apply a callback function to all elements in an array. The callback function must accept a parameter that represents the element in the input array. In the callback function, we can process the elements and return the processed results. Finally, the array_map() function returns a new array containing all processed elements.

Note that when using the array_map() function, the keys of the input array will be retained in the output array.

The following is an example that demonstrates how to use the array_map() function to change the keys of an array:

// 原始数组
$originalArray = array(
    'name' => 'John',
    'age' => 35,
    'gender' => 'male'
);

// 使用array_map()更改键名
$newArray = array_map(function($value) {
    $newKey = str_replace('_', ' ', $value);
    $newKey = ucwords($newKey);
    $newKey = str_replace(' ', '', $newKey);
    return $newKey;
}, array_keys($originalArray), array_fill(0, count($originalArray), null));

$newArray = array_combine($newArray, $originalArray);

// 输出新的数组
var_dump($newArray);

In this example, we define an anonymous function that uses the input key name Some string functions return after processing. We use the array_keys() function to get all the keys of the original array, and then use the array_fill() function to generate an array with the same length as the key array, so that we can pass these two arrays to the array_map() function. Finally, we combine the processed key name array and the original array value into a new array, completing the key name change.

3. Use foreach loop

Finally, we can use foreach loop to traverse the original array and create a new array with new key names. During the traversal process, we need to assign the keys and values ​​of the original array to variables $key and $value respectively, and then create a new array item using a new key name $newKey. At the end of the traversal, we get a completely different array in which the key names have been changed.

The following is an example that demonstrates how to use a foreach loop to change the keys of an array:

// 原始数组
$originalArray = array(
    'name' => 'John',
    'age' => 35,
    'gender' => 'male'
);

// 新键名
$newKeys = array(
    'person_name',
    'person_age',
    'person_gender'
);

// 使用foreach循环更改键名
$newArray = array();
foreach($originalArray as $key => $value) {
    $newKey = $newKeys[$key];
    $newArray[$newKey] = $value;
}

// 输出新的数组
var_dump($newArray);

In this example, we first define the original array $originalArray and a new key array$ newKeys. We then use a foreach loop to iterate over the original array. In each loop, we find the corresponding new key name $neKey in the new key name array based on the key $key of the current cycle, and then create a new array item $newArray[$newKey] = $value. After the loop ends, we get a new array $newArray in which the key names have been changed.

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