php array writing method

PHP is a powerful server-side scripting language that is widely used in web development. In PHP, array is a very important data type that allows us to store multiple values ​​in one variable. This article will introduce how to write arrays in PHP.

1. Declare array variables

In PHP, array variables can be declared as follows:

// 声明一个空数组
$arr = array();

// 声明一个带有元素的数组
$arr = array('apple', 'orange', 'banana');

In addition, starting from PHP 5.4 version, also Array variables can be declared using simplified syntax:

// 空数组
$arr = [];

// 带有元素的数组
$arr = ['apple', 'orange', 'banana'];

2. Declaration of associative array

Associative array is a special type of array that allows us to Associated with a key so that the element can be accessed using that key. In PHP, an associative array is written as follows:

// 声明一个带有键的关联数组
$arr = array(
    'name' => 'Tom',
    'age' => 20,
    'gender' => 'male'
);

You can also use simplified syntax to declare an associative array:

// 带有键的关联数组
$arr = [
    'name' => 'Tom',
    'age' => 20,
    'gender' => 'male'
];

3. Access array elements

In PHP, you can use subscripts to access elements in an array. An array subscript is a numeric value or string that represents a specific element in the array. Array subscripts start counting from 0.

$arr = array('apple', 'orange', 'banana');
echo $arr[0];  // 输出 "apple"
echo $arr[1];  // 输出 "orange"
echo $arr[2];  // 输出 "banana"

// 关联数组的访问方式
$info = array(
    'name' => 'Tom',
    'age' => 20,
    'gender' => 'male'
);
echo $info['name'];    // 输出 "Tom"
echo $info['age'];     // 输出 20
echo $info['gender'];  // 输出 "male"

4. Modify array elements

In PHP, you can modify the elements in the array through the array subscript.

$arr = array('apple', 'orange', 'banana');
$arr[1] = 'pear';
print_r($arr);  // 输出 Array ( [0] => apple [1] => pear [2] => banana )

// 修改关联数组的值
$info = array(
    'name' => 'Tom',
    'age' => 20,
    'gender' => 'male'
);
$info['name'] = 'Jerry';
print_r($info);  // 输出 Array ( [name] => Jerry [age] => 20 [gender] => male )

5. Traverse an array

In PHP, you can use a foreach loop to iterate through all elements in an array.

$arr = array('apple', 'orange', 'banana');
foreach ($arr as $value) {
    echo $value . ' ';  // 输出 "apple orange banana "
}

// 遍历关联数组
$info = array(
    'name' => 'Tom',
    'age' => 20,
    'gender' => 'male'
);
foreach ($info as $key => $value) {
    echo $key . ':' . $value . ' ';  // 输出 "name:Tom age:20 gender:male "
}

The above is how to write PHP arrays, I hope it can help everyone.

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