How to assign values ​​to php associative arrays (two methods)

In PHP, an associative array is composed of key-value pairs, where the key is a string and the value can be a string, number, Boolean value or any other data type. The assignment operation can be performed in the following two ways:

1. Directly use the "key => value" syntax

// 创建空数组
$arr = array();

// 直接赋值
$arr['name'] = 'Tom';
$arr['age'] = 20;
$arr['country'] = 'China';

In this way, we create an element containing three elements An associative array, each element contains a key and a value.

2. Use the array() function to create an associative array

// 使用array()函数创建关联数组
$arr = array(
    'name' => 'Tom',
    'age' => 20,
    'country' => 'China'
);

This method is very similar to the Map collection in Java. We can specify all of the arrays immediately when creating the array. Key-value pairs.

In PHP, the key of an associative array can be any string or integer, and the value can be any data type, so we can create an associative array containing different data types:

// 声明关联数组
$user = array(
    'name'   => 'Tom',
    'age'    => 20,
    'gender' => true,
    'address'=> array(
        'city' => 'Shanghai',
        'street' => 'Nanpu Bridge'
    )
);

// 访问关联数组元素
echo $user['name'], '<br>';  // 输出Tom
echo $user['gender'], '<br>'; // 输出1，因为true被视为1
echo $user['address']['city'], '<br>'; // 输出Shanghai

In this example, we create a nested associative array that contains a string value, a boolean value, and an array containing two string values. We also showed how to access elements of an associative array. We can access an element using the array name and key. If the element is an array, we can access its children by accessing its key.

Be careful when using associative arrays, each key must be unique, if you try to use the same key name twice, the original value will be overwritten. At the same time, we can use the keyword unset() to delete a specific key and its value.

// 定义关联数组
$user = array(
    'name'   => 'Tom',
    'age'    => 20,
    'gender' => true,
    'address'=> array(
        'city' => 'Shanghai',
        'street' => 'Nanpu Bridge'
    )
);

// 删除关联数组元素
unset($user['gender']); // 删除gender键和值
unset($user['address']['street']); // 删除address中的street键和值

// 打印结果
print_r($user);

To summarize, PHP's associative array can be assigned using key-value pairs. You can use the array() function to create an associative array. The key (key) of the associative array can be any string or integer, and the value (value) can be of any data type. Also note that each key must be unique, if duplicated the original value will be overwritten. To delete specific keys and values ​​from an associative array, use the unset() function.

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