PHP deletes a key from a two-dimensional array

In PHP programming, we often need to operate arrays. Sometimes, we need to delete a key in the array. This article will introduce how to delete a key of a two-dimensional array through PHP code.

In PHP, an array is a variable used to store multiple values. Each value in the array has a key and a value. A value in an array can be accessed by key. Arrays in PHP are divided into one-dimensional arrays and multi-dimensional arrays. A one-dimensional array is an array with only one key and one value. A multidimensional array is an array containing multiple keys and values, where each value can also be an array.

To delete a key in the array, you can use PHP's unset() function. This function can be used to delete any type from a variable, including arrays and objects.

Example:

Suppose there is a two-dimensional array $arr:

$arr = array(
    array("id"=>1, "name"=>"Tom", "age"=>20),
    array("id"=>2, "name"=>"Jerry", "age"=>22),
    array("id"=>3, "name"=>"Mickey", "age"=>18)
);

If you want to remove the "id" key of each element in the $arr array. You can use the following code:

foreach ($arr as &$value) {
    unset($value['id']);
}

The above code uses a foreach loop to assign each element in the array to the $value variable in turn. Then use the unset() function to delete the "id" key in the $value variable.

It should be noted that reference variables (&$value) are used here. This is because the array $arr is a two-dimensional array. If a reference variable is not used, the unset() function will only delete the key value in the $value variable without affecting the original array $arr.

If you only need to delete a key of one element in the array, you can use the following code:

unset($arr[0]['id']);

The above code will delete the "id" key of the first element in the array $arr.

Summary:

In PHP, you can use the unset() function to delete a key of a two-dimensional array. You can use a foreach loop to delete a key of each element in the array, or you can directly use the unset() function to delete a key of a specified element in the array. It should be noted that if it is a two-dimensional array, reference variables need to be used.

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