php change identity array content

In PHP, array is a very commonly used data structure. In actual development, we often need to operate arrays, including adding, deleting, modifying, etc. In this article, we will explore how to change the identity array contents.

First, we need to understand the two array types in PHP: index array and associative array. Indexed arrays are accessed based on the subscript of the array, while associative arrays are accessed based on the key-value pairs of the array. In this article, we focus primarily on associative arrays.

Changing the value of an associative array is very simple. We just need to access the array element by key name and update its value to the new value. Here is a simple example:

<?php
$friends = array(
    "Alice" => 23,
    "Bob" => 28,
    "Charlie" => 31,
    "David" => 19
);

// 修改Alice的年龄
$friends['Alice'] = 24;

print_r($friends);
?>

The above code will output the following:

Array
(
    [Alice] => 24
    [Bob] => 28
    [Charlie] => 31
    [David] => 19
)

As you can see, we pass $friends['Alice'] = 24 Update Alice's age to 24.

There is another way to change the value of an associative array, which is to use the array_replace function. This function can merge the key-value pairs of one or more arrays into one array and replace the values ​​with the same key name. Here is an example:

<?php
$friends = array(
    "Alice" => 23,
    "Bob" => 28,
    "Charlie" => 31,
    "David" => 19
);

$new_friends = array(
    "Alice" => 24,
    "Bob" => 29
);

$friends = array_replace($friends, $new_friends);

print_r($friends);
?>

The above code will output the following:

Array
(
    [Alice] => 24
    [Bob] => 29
    [Charlie] => 31
    [David] => 19
)

As you can see, we use the array_replace function to $new_friends The value in the array replaces the value with the same key in the $friends array.

It should be noted here that the array_replace function will merge the key-value pairs of the two arrays, and the key-value pairs in the later array will overwrite the key-value pairs in the previous array. Key-value pairs. If there are extra key names in the subsequent array, they will be appended to the merged array.

In addition to the above methods, we can also use the foreach loop to traverse the associative array and update the corresponding value through the key name. Here is an example:

<?php
$friends = array(
    "Alice" => 23,
    "Bob" => 28,
    "Charlie" => 31,
    "David" => 19
);

// 将所有年龄都加1
foreach ($friends as $name => $age) {
    $friends[$name] = $age + 1;
}

print_r($friends);
?>

The above code will output the following:

Array
(
    [Alice] => 24
    [Bob] => 29
    [Charlie] => 32
    [David] => 20
)

As you can see, we looped through $friends## through foreach # Array and use the key name to update the value of each element.

In short, in PHP, changing the value of an associative array is very simple. We can access the element directly by key name and update its value to a new value, or use the

array_replace function or the foreach loop to change the value of multiple elements. These methods are very flexible and can be selected and used according to the specific situation.

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