Convert an array or object to a JSON string using PHP's json_encode() function

JSON (JavaScript Object Notation) is a lightweight data exchange format that has become a common format for data exchange between web applications. PHP's json_encode() function can convert an array or object into a JSON string. This article will introduce how to use PHP's json_encode() function, including syntax, parameters, return values, and specific examples.

1. Syntax

The syntax of the json_encode() function is as follows:

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

Among them, the $value parameter represents the value to be converted to a JSON string, which can be Is an array or object. The $options parameter represents the options when converting JSON strings. The optional values ​​are as follows:

• JSON_HEX_TAG: Encode all "<", ">" and other mark characters into hexadecimal format (u003C, u003E, etc.)
• JSON_HEX_QUOT: Encode all double quote characters into hexadecimal format (u0022)
• JSON_HEX_AMP: Encode all & characters into hexadecimal format (u0026)
• JSON_HEX_APOS: Encode all single quote characters into hexadecimal format (u0027)
• JSON_NUMERIC_CHECK: Convert all strings to numbers (integers or floating point numbers), If possible
• JSON_PRETTY_PRINT: Formatted JSON string with indentation and newlines
• JSON_UNESCAPED_SLASHES: Do not escape backslash characters ()
• JSON_FORCE_OBJECT: Will Convert non-associative arrays to objects

The $depth parameter indicates the limit of the recursion depth, which is used to prevent stack overflow. The default is 512.

2. Parameters

When using the json_encode() function, you need to pay attention to the following points:

• $value parameters can only be arrays or Object, if not, return null
• The object cannot be converted directly, the object needs to be converted into an array first
• The JSON_PRETTY_PRINT option will increase character processing overhead and have a certain impact on performance
• You need to pay attention to overflow issues when converting long strings

3. Return value

json_encode() function returns a string in JSON data format, and returns if an error occurs FALSE. If the JSON_PRETTY_PRINT option is used, the returned string will have indentation and newlines. You can use the echo or var_dump function to output it.

4. Example

The following shows two specific examples of using the json_encode() function.

1) Convert the array to a JSON string

<?php
$data = array('name'=>'Tom','age'=>18,'gender'=>'male');
$json = json_encode($data);
echo $json;
?>

Output result:

{"name":"Tom","age":18,"gender":"male"}

2) Convert the object to a JSON string

<?php
class Person {
  public $name;
  public $age;
  public $gender;
}

$person = new Person();
$person->name = "Tom";
$person->age = 18;
$person->gender = "male";

$json = json_encode($person);
echo $json;
?>

Output result ：

{"name":"Tom","age":18,"gender":"male"}

To sum up, you can easily convert an array or object into a JSON string using PHP’s json_encode() function. Developers can select appropriate options to control the formatting and escaping of JSON strings as needed.

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