What are the commonly used arrays in php?

Commonly used arrays in php are: 1. Index array. Index array is the most commonly used array type. Each element of it has an integer subscript, starting from 0 and increasing. 2. Associative array, each element of which has a string key; 3. Multi-dimensional array, which can create multi-dimensional arrays of any level; 4. Arrays with variable keys, which can dynamically add and delete key-value pairs array.

The operating environment of this tutorial: windows10 system, php8.1.3 version, Dell G3 computer.

In PHP, there are four types of arrays:

1. Index array: Index array is the most commonly used array type. Each element of it has an integer subscript. Starting from 0 and increasing. You can create an index array in the following two ways:

$arr = array('apple', 'banana', 'orange');
$arr = ['apple', 'banana', 'orange'];

2. Associative array: An associative array is also called a hash table or dictionary, and each element of it has a string key. You can create an associative array in the following two ways:

$arr = array('name' => 'Tom', 'age' => 20, 'gender' => 'male');
$arr = ['name' => 'Tom', 'age' => 20, 'gender' => 'male'];

3. Multidimensional array: A multidimensional array means that the array contains another array, and you can create a multidimensional array of any level.

$arr = array(
array('apple', 'banana', 'orange'),
array('Tom', 'Jerry', 'Mickey'),
array('male', 'female', 'unknown')
);

4. Arrays with variable keys: Arrays with variable keys refer to arrays that can dynamically add and delete key-value pairs, such as parameter arrays obtained using $_GET and $_POST.

To distinguish these four array types, you can use the is_array() function to determine whether it is an array, use the array_key_exists() function to determine whether the specified key exists, use the count() function to obtain the array length, and use var_dump () function prints array structure, etc.

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