PHP returns all keys of the array to form an array

php editor Strawberry will introduce you to a practical technique today: how to form a new array with all the keys of the array. In PHP, we can use the array_keys() function to achieve this function. This function can return a new array containing all the keys of the original array, allowing us to easily operate and process the keys of the array. Next, let’s take a look at the specific implementation method!

PHP Get all keys of the array:

Overview:

php Provides multiple methods to get all the keys in the array to form a new array. This article will explore these methods and their nuances to help you make an informed choice based on your specific needs.

method:

1. array_keys()

array_keys() The function returns an array of all keys in the array. It accepts an array as parameter and returns an array containing the key values.

$fruits = ["apple", "banana", "orange"];
$keys = array_keys($fruits); // [0, 1, 2]

2. keys()

keys() is an alias of the array_keys() function with the same behavior and usage.

3. array_map() array_keys()

This method utilizes the array_map() function to apply array_keys() to each value in the array. The result is a new array containing all keys.

$keys = array_map("array_keys", $fruits); // [0, 1, 2]

4. array_column()

array_column() Function can be used to extract the values ​​of a specific column from a multidimensional array. It can also be used as an alternative method of extracting keys.

$data = [
["id" => 1, "name" => "John"],
["id" => 2, "name" => "Mary"],
];
$keys = array_column($data, "id"); // [1, 2]

5. foreach loop

foreach A loop iterates through each element in the array and accesses the key by using the key key.

$keys = [];
foreach ($fruits as $key => $value) {
$keys[] = $key;
}

6. IteratorAggregate interface

Objects that implement the IteratorAggregate interface can access keys through iterators. You can get an iterator and get keys from it using the getIterator() method.

class MyArray implements IteratorAggregate {
public function getIterator() {
return new ArrayIterator($this->data);
}
}
$arr = new MyArray();
$keys = [];
foreach ($arr as $key => $value) {
$keys[] = $key;
}

Performance comparison:

The following is a rough performance comparison of different methods:

• array_keys(): Fastest
• array_map() array_keys(): Faster
• keys(): Same as array_keys()
• array_column(): Efficient for multi-dimensional arrays
• foreach Loop: poor performance
• IteratorAggregate: Higher complexity

Method of choosing:

Choosing the method that best suits your needs depends on the following factors:

• Structure of array
• Number of arrays to be processed
• Performance Priority

For simple and small arrays, array_keys() or array_map() array_keys() are the best choices. For large and multidimensional arrays, array_column() may be more appropriate. For complex objects, IteratorAggregate is a viable option.

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