How to convert json object to PHP array

json is a lightweight data exchange format that is becoming more and more popular. PHP is an excellent server-side programming language that is ideal for web development. Therefore, converting json objects to PHP arrays is a very useful skill. In this article, we will learn how to convert json object to PHP array.

1. json_decode() function

The json_decode() function in PHP is the main way to convert a json-formatted string into a PHP variable (array or object). The syntax is as follows:

mixed json_decode(string $json[, bool $assoc = FALSE[, int $depth = 512[, int $options = 0]]])

Parameter description:

• json: json string.
• assoc: A Boolean value indicating whether to convert the json object to an associative array.
• depth: Integer type, indicating the maximum depth. By default, the maximum depth is 512, which can be defined using the constant JSON_DEPTH.
• options: Options for more fine-grained control of the decoding process. Combinations of the following constants can be used:

Constant	Description
JSON_BIGINT_AS_STRING	Available in PHP 5.4.0 and higher. Convert integers greater than PHP_INT_MAX to strings.
JSON_INVALID_UTF8_IGNORE JSON_INVALID_UTF8_SUBSTITUTE	Available in PHP 5.3.3 and later. JSON_INVALID_UTF8_IGNORE This option will ignore illegal UTF-8 characters. JSON_INVALID_UTF8_SUBSTITUTE This option will replace illegal UTF-8 characters with Unicode replacement characters.
JSON_OBJECT_AS_ARRAY	Convert json object to associative array.
JSON_THROW_ON_ERROR Available in PHP 7.3.0 and higher. This constant is used to automatically throw an exception instead of returning FALSE.

Example:

The following is the JSON string:

{
  "name": "John Doe",
  "age": 30,
  "city": "New York"
}

Use json_decode () Function converts it into an associative array:

$json = '{"name":"John Doe","age":30,"city":"New York"}';
$arr = json_decode($json, true);

print_r($arr);

Output:

Array
(
    [name] => John Doe
    [age] => 30
    [city] => New York
)

2. json_decode() function usage notes

• json_decode() can only handle UTF-8 encoded data.
• json_decode() only supports data types used in PHP, such as strings, numbers, arrays, and objects.
• json_decode() does not support special data types such as resources and callback functions.
• json_decode() only supports json strings with double quotes. Do not use single quotes or unquoted key names.
• When given to the json_encode() function, use the constant JSON_UNESCAPED_UNICODE to ensure that non-ASCII characters are escaped.

3. Example

Here is the complete example of converting a json string to a PHP array:

<?php
// 1. 定义 json 格式的字符串
$json = &#39;{"name":"John Doe","age":30,"city":"New York"}&#39;;

// 2. 将 json 格式的字符串转换为 PHP 数组
$arr = json_decode($json, true);

// 3. 输出转换后的数组
print_r($arr);
?>

Output:

Array
(
    [name] => John Doe
    [age] => 30
    [city] => New York
)

4. Conclusion

As mentioned above, we can use the json_decode() function to convert the json object into a PHP array. This technique is very useful in web development and helps us parse JSON data from AJAX calls.

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