Data encoding and data decoding in PHP using JSON

With the widespread use of Web applications, data encoding and decoding has become a necessary process. In PHP, using JSON (JavaScript Object Notation) for data encoding and data decoding has become a very popular and common way.

JSON is a lightweight data exchange format that represents data in the form of JavaScript objects and can facilitate string transmission and parsing. In PHP, using JSON for data encoding and data decoding is very simple and only requires a small amount of code to implement.

There are many ways to implement JSON in PHP. You can use native PHP functions or combine it with third-party libraries. However, in versions after PHP 5.2, it comes with two functions, json_encode() and json_decode(), which can easily perform data encoding and decoding.

The following is a detailed introduction to the usage of these two functions:

json_encode() function:

json_encode() function can convert PHP arrays or objects into JSON strings . Its syntax is as follows:

string json_encode(mixed $value, int $options = 0, int $depth = 512)

Among them, the $value parameter is required and represents the value to be encoded ; The $options parameter is used to set encoding options, which can be one of the following values:

JSON_HEX_TAG: Convert all '' to 'u003C' and 'u003E', you can Prevent XSS attacks.

JSON_HEX_APOS: Convert all single quotes to 'u0027' to avoid quote conflicts in strings.

JSON_HEX_QUOT: Convert all double quotes to 'u0022' to avoid quote conflicts in the string.

JSON_HEX_AMP: Convert all '&' to 'u0026' to avoid problems when submitting the form.

JSON_UNESCAPED_SLASHES: Do not escape slashes.

JSON_PRETTY_PRINT: Use spaces for formatting.

The $depth parameter is used to set the depth of serialization, which can avoid infinite loops caused by mutual references of arrays or objects. The default value is 512, which can be set to 0 to limit the depth.

For example, to encode a PHP array into a JSON string you can use the following code:

$arr ​​= array('name'=>'John', 'age'=>30, 'city'=>'New York');
echo json_encode($arr);
?>

The output result is:

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

json_decode() function:

json_decode() function can Convert JSON string to PHP array or object. Its syntax is as follows:

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

Among them, the $json parameter is required , indicating the JSON string to be decoded; the $assoc parameter is used to set the data type returned after decoding, which can be one of the following values:

false: Returns an object.

true: Returns an associative array.

The $depth parameter is used in the same way as the json_encode() function and is used to avoid infinite loops caused by mutual references of objects or arrays; the $options parameter is used to set options during decoding, which can be one of the following values ：

JSON_BIGINT_AS_STRING: Convert the large integer in the JSON string into a string.

For example, to decode a JSON string into a PHP array you can use the following code:

$json = '{"name":"John","age" :30,"city":"New York"}';
print_r(json_decode($json));
?>

The output result is:

stdClass Object
(

[name] => John
[age] => 30
[city] => New York

)

Conclusion:

In terms of practicality and compatibility, JSON has become one of the most popular data formats currently. Using JSON for data encoding and data decoding in PHP is also a very convenient, fast and stable method. Mastering the use of the json_encode() and json_decode() functions will make developers' work more efficient and simpler.

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