How to delete a certain value in a two-dimensional array in php

PHP is a scripting language widely used in Web development. Many Web applications are developed based on PHP. In PHP development, array operations are often involved, and deleting a certain value in an array is also one of the common operations. This article will introduce how to delete a certain value in a two-dimensional array in PHP.

First, let’s take a look at the basic operations of arrays in PHP.

1. Create an array
   Creating an array in PHP can be accessed using the following two forms:

$arr = array('a', 'b', 'c');

and

$arr = ['a', 'b', 'c'];

2. Array elements
   You can access array elements through subscripts. The subscripts start counting from 0. The example is as follows:

$arr = ['a', 'b', 'c'];
echo $arr[0]; // 输出 a

3. Traverse the array
   There are many ways to traverse the array in PHP , the most common is to use a foreach loop, the example is as follows:

$arr = ['a', 'b', 'c'];
foreach ($arr as $value) {
  echo $value . ' ';
}

The output result is:

a b c

The above is the basic operation of arrays in PHP. Next, let’s look at deleting two-dimensional Method for a value in an array.

To delete a certain value in a two-dimensional array, you can use the unset() function. If you want to delete a certain value in a one-dimensional array, you can use the unset() function directly. However, there are two ways to delete a certain value in a two-dimensional array, namely traversal and array_map() function.

1. Traversal implementation

Traverse the array and delete it using the unset() function. The example is as follows:

$arr = [
    ['name' => 'Amy', 'age' => 20],
    ['name' => 'Bob', 'age' => 22],
    ['name' => 'Cathy', 'age' => 18]
];

foreach ($arr as $key => $value) {
    if ($value['name'] == 'Bob') {
        unset($arr[$key]);
    }
}

print_r($arr);

Execute the above code and the output result is:

Array
(
    [0] => Array
        (
            [name] => Amy
            [age] => 20
        )

    [2] => Array
        (
            [name] => Cathy
            [age] => 18
        )

)

By traversing the two-dimensional array, find the element to be deleted, delete it using the unset() function, and finally output the remaining array.

2. array_map() function implementation

The array_map() function can return each element of one or more arrays after being processed by a callback function. Use it to find the element to be deleted first, and then process and return the remaining array. The example is as follows:

$arr = [
    ['name' => 'Amy', 'age' => 20],
    ['name' => 'Bob', 'age' => 22],
    ['name' => 'Cathy', 'age' => 18]
];

$name = 'Bob';

$arr = array_map(function($value) use ($name) {
    if ($value['name'] == $name) {
        return null;
    }
    return $value;
}, $arr);

$arr = array_filter($arr, function($value) {
    return $value !== null;
});

print_r($arr);

Execute the above code, and the output result is:

Array
(
    [0] => Array
        (
            [name] => Amy
            [age] => 20
        )

    [2] => Array
        (
            [name] => Cathy
            [age] => 18
        )

)

In the above code example, the array_map() function is used. First, pass $name to the callback function through the use keyword, find the element to be deleted, and return null. Then, use the array_filter() function to filter out null elements and get the remaining array.

Summary: To delete a certain value in a two-dimensional array in PHP, you can use the unset() function or the array_map() function. Whichever method is used can be used to process two-dimensional arrays, and you can choose according to the actual usage scenario.

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