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JSON (JavaScript Object Notation) is a lightweight format used to exchange data between the client and server. PHP provides built-in functions like json_encode() to convert PHP arrays/objects to JSON and json_decode() to parse JSON into PHP. This is essential for APIs, AJAX, and file handling. You can also read/write JSON files using file_get_contents() and file_put_contents(). PHP and JSON together enable efficient, structured data exchange in web applications.

1. What is JSON?

• JSON is a text format for storing and transporting data.
• Example JSON:

{
  "name": "John",
  "age": 25
}

2. json_encode() – Convert PHP to JSON

$data = [
    "name" => "John",
    "age" => 25,
    "skills" => ["PHP", "Laravel", "MySQL"]
];

$json = json_encode($data);
echo $json;

File: json_encode_demo.php

Output:

{"name":"John","age":25,"skills":["PHP","Laravel","MySQL"]}

3. json_decode() – Convert JSON to PHP

$jsonString = '{"name":"John","age":25}';

$data = json_decode($jsonString, true); // true = associative array
echo $data["name"]; // Output: John

File: json_decode_demo.php

4. Working with Objects from JSON

$jsonString = '{"name":"John","age":25}';

$data = json_decode($jsonString); // default = object
echo $data->name; // Output: John

5. Send JSON from PHP to JavaScript (AJAX)

header('Content-Type: application/json');

$response = [
    "status" => "success",
    "message" => "Data received"
];

echo json_encode($response);

File: api_response.php

6. Save JSON to a File

$data = ["user" => "John", "role" => "admin"];
$jsonData = json_encode($data, JSON_PRETTY_PRINT);

file_put_contents("data.json", $jsonData);

File: json_write.php

7. Read JSON File

$jsonContent = file_get_contents("data.json");
$data = json_decode($jsonContent, true);

print_r($data);

File: json_read.php

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