PHP removes hollow arrays from two-dimensional arrays

In PHP programming, we often need to use arrays to store and manage data. Sometimes, we encounter empty arrays in some two-dimensional arrays. These empty arrays may be caused by improper data processing or other reasons. When performing data operations, these empty arrays will interfere with the results, causing program running errors or inaccurate results. Therefore, we need to learn to remove empty arrays in two-dimensional arrays in order to better utilize the data for data processing.

This article will introduce how to use PHP to remove empty arrays from two-dimensional arrays. This article will elaborate on the following aspects:

1. What is a two-dimensional array
2. What is an empty array
3. How to remove empty arrays from a two-dimensional array
4. Example demonstration
5. What is a two-dimensional array

A two-dimensional array refers to an array containing multiple arrays, and each array can contain multiple elements. For example:

$users = array(
    array('name'=>'张三','age'=>20),
    array('name'=>'李四','age'=>22),
    array('name'=>'王五','age'=>25)
);

In the above code, $users is a two-dimensional array, containing three arrays, each array has two elements: name and age. We can access them through subscripts, for example: $users0 can get the name of the first element in the array.

2. What is an empty array

An empty array means there are no elements in an array. For example:

$empty_array = array();

In PHP programming, we sometimes need to determine whether an array is empty. We can use the empty() function to determine. Returns true if the array is empty, false otherwise. For example:

if(empty($empty_array)){
    echo "数组为空";
}else{
    echo "数组不为空";
}

3. How to remove empty arrays in two-dimensional arrays

In actual development, we often encounter situations where empty arrays exist in two-dimensional arrays. These empty arrays may interfere with data processing. Therefore, we need to learn how to remove these empty arrays in order to better utilize the data for data processing.

In PHP, you can use the array_filter() function to remove empty arrays from an array. The function of the array_filter() function is to pass the elements in the array into the user-defined function in sequence. If the function returns TRUE, the element will be retained in the array, otherwise, the element will be deleted from the array. For example:

$array = array("a", "b", "", "c", "");
$array = array_filter($array);
print_r($array);

In the above code, $array contains 5 elements, of which the 3rd and 5th elements are empty strings. After using the array_filter() function, these two elements will be removed, and the final output result is:

Array
(
    [0] => a
    [1] => b
    [3] => c
)

It can be seen that the array_filter() function can easily remove empty elements in the array. Similarly, the array_filter() function can also be used in a two-dimensional array, for example:

$users = array(
    array('name'=>'张三','age'=>20,'sex'=>'男'),
    array(),
    array('name'=>'李四','age'=>22,'sex'=>'女'),
    array('name'=>'王五','age'=>25,'sex'=>'男')
);

foreach ($users as &$user) {
    $user = array_filter($user);
}

unset($user);

print_r($users);

In the above code, $users is a two-dimensional array, and the second array is an empty array. When looping through an array, use the array_filter() function to remove empty arrays. The final output result is:

Array
(
    [0] => Array
        (
            [name] => 张三
            [age] => 20
            [sex] => 男
        )

    [1] => Array
        (
            [name] => 李四
            [age] => 22
            [sex] => 女
        )

    [2] => Array
        (
            [name] => 王五
            [age] => 25
            [sex] => 男
        )

)

It can be seen that using the array_filter() function can easily remove empty arrays in two-dimensional arrays.

4. Example Demonstration

The following is a complete example that demonstrates how to remove empty arrays from a two-dimensional array:

After executing the above code, Output the two-dimensional array after removing the empty array.

Summary

This article introduces how to use PHP to remove empty arrays in two-dimensional arrays, including what is a two-dimensional array, what is an empty array, and how to remove empty arrays in a two-dimensional array and example demonstrations, etc. When we need to perform data processing, we need to learn how to deal with empty arrays that exist in the array to ensure the correctness of the program and the accuracy of the results.

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