PHP two-dimensional array value modification

For two-dimensional arrays in PHP, we usually need to update or modify the values ​​in the array. This operation is very common in development, so this article will introduce how to modify the value of a two-dimensional array in PHP.

In PHP, we can use many methods to modify the value of a two-dimensional array. Several methods are introduced below.

Method 1: Use foreach loop

Using foreach loop can easily traverse each element in the two-dimensional array and make corresponding modifications.

For example, we have the following two-dimensional array:

$array = array(
    array('name' => '小明', 'age' => 20), 
    array('name' => '小红', 'age' => 18),
    array('name' => '小张', 'age' => 22)
);

Now we want to change Xiaohong’s age to 19, we can use the following code:

foreach ($array as $key => $value) {
    if ($value['name'] == '小红') {
        $array[$key]['age'] = 19;
    }
}

Here we use a foreach loop to traverse each element in the array, and then determine whether its name is Xiaohong. If so, change its age to 19.

Method 2: Use array_map function

The array_map function can apply a function to each element of the array and return a new array. You can use this function to modify certain elements in a two-dimensional array.

For example, we have the following two-dimensional array:

$array = array(
    array('name' => '小明', 'age' => 20), 
    array('name' => '小红', 'age' => 18),
    array('name' => '小张', 'age' => 22)
);

Now we want to change Xiao Ming’s age to 21, you can use the following code:

function modify_age($value)
{
    if ($value['name'] == '小明') {
        $value['age'] = 21;
    }
    return $value;
}

$array = array_map('modify_age', $array);

Here We define a function modify_age to modify the value of an element. This function is then applied to each element of the array using the array_map function, and a new, modified array is returned.

Method 3: Directly access the elements of the two-dimensional array

The last method is to directly access the elements of the two-dimensional array for modification. This method is the simplest, but you need to know the position of the element to be modified.

For example, we have the following two-dimensional array:

$array = array(
    array('name' => '小明', 'age' => 20), 
    array('name' => '小红', 'age' => 18),
    array('name' => '小张', 'age' => 22)
);

Now we want to change Xiao Zhang’s age to 23, we can use the following code:

$array[2]['age'] = 23;

Here we directly access the age attribute of the third element in the array and assign it a value of 23.

Summary

The above are the methods of modifying two-dimensional arrays in PHP. Among them, the method of using foreach loop and direct access to array elements is the most common and simple, while the method of using array_map function is more flexible and Scalable. Which method to use can be chosen according to the actual situation.

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