Explain PHP JSON

PHP provides built-in functions to work with JSON (JavaScript Object Notation), a popular data interchange format. These functions are json_encode and json_decode.

Encoding JSON

json_encode converts a PHP variable (such as an array or object) into a JSON string.

Example 1: Encoding an array to JSON

<?php
$data = array(
    "name" => "John Doe",
    "age" => 30,
    "city" => "New York"
);

$json = json_encode($data);
echo $json;  // Output: {"name":"John Doe","age":30,"city":"New York"}
?>

Example 2: Encoding a multi-dimensional array

<?php
$data = array(
    "employees" => array(
        array("name" => "John Doe", "age" => 30, "city" => "New York"),
        array("name" => "Jane Doe", "age" => 25, "city" => "Los Angeles")
    ),
    "company" => "Tech Solutions"
);

$json = json_encode($data, JSON_PRETTY_PRINT);
echo $json;
/*
Output:
{
    "employees": [
        {
            "name": "John Doe",
            "age": 30,
            "city": "New York"
        },
        {
            "name": "Jane Doe",
            "age": 25,
            "city": "Los Angeles"
        }
    ],
    "company": "Tech Solutions"
}
*/
?>

Decoding JSON

json_decode converts a JSON string into a PHP variable.

Example 1: Decoding a JSON string to an associative array

<?php
$json = '{"name":"John Doe","age":30,"city":"New York"}';

$data = json_decode($json, true);
print_r($data);
/*
Output:
Array
(
    [name] => John Doe
    [age] => 30
    [city] => New York
)
*/
?>

Example 2: Decoding a JSON string to an object

<?php
$json = '{"name":"John Doe","age":30,"city":"New York"}';

$data = json_decode($json);
echo $data->name;  // Output: John Doe
echo $data->age;   // Output: 30
echo $data->city;  // Output: New York
?>

Example 3: Handling complex JSON structure

<?php
$json = '{
    "employees": [
        {"name": "John Doe", "age": 30, "city": "New York"},
        {"name": "Jane Doe", "age": 25, "city": "Los Angeles"}
    ],
    "company": "Tech Solutions"
}';

$data = json_decode($json, true);
print_r($data);
/*
Output:
Array
(
    [employees] => Array
        (
            [0] => Array
                (
                    [name] => John Doe
                    [age] => 30
                    [city] => New York
                )

            [1] => Array
                (
                    [name] => Jane Doe
                    [age] => 25
                    [city] => Los Angeles
                )

        )

    [company] => Tech Solutions
)
*/
?>

Handling JSON Errors

PHP provides json_last_error and json_last_error_msg functions to check for errors during JSON encoding or decoding.

Example: Checking for JSON errors

<?php
$json = '{"name":"John Doe", "age":30, "city":"New York"'; // Missing closing }

$data = json_decode($json);
if (json_last_error() != JSON_ERROR_NONE) {
    echo "JSON Error: " . json_last_error_msg();  // Output: JSON Error: Syntax error
}
?>

These are the basic operations you can perform with JSON in PHP. Using json_encode and json_decode, you can easily convert between PHP data structures and JSON format for data interchange.