How to define associative array in php

In PHP, an associative array is a data type that stores data in the form of key-value pairs. Unlike ordinary arrays, the keys of associative arrays can be any strings, not just numbers or indices.

There are two ways to define an associative array:

1. Direct definition

You can directly define an associative array. The definition format is as follows:

$array = array(
    'key1' => 'value1',
    'key2' => 'value2',
    'key3' => 'value3'
);

Among them, key1, key2, key3 are key names, value1, value2, value3 is the corresponding value.

2. Dynamic addition

Associative arrays can also dynamically add elements after definition. The example is as follows:

$array = array();

$array['key1'] = 'value1';
$array['key2'] = 'value2';
$array['key3'] = 'value3';

Use [] The operator can dynamically add elements. If the element does not exist, a new element will be created.

It should be noted that the key name must be unique. If the same key name is used multiple times, the subsequent value will overwrite the previous value.

$array = array(
    'key1' => 'value1',
    'key2' => 'value2'
);

$array['key1'] = 'new value';
/* 此时 $array 变为：
  array(
      'key1' => 'new value',
      'key2' => 'value2'
  );
*/

The above are two methods of defining associative arrays. You can choose the method that suits you according to your needs.

The above is the detailed content of How to define associative array in php. For more information, please follow other related articles on the PHP Chinese website!