JSON in PHP (json_encode, json_decode)

What is JSON

JSON (JavaScript Object Notation) is a lightweight text format for storing and sending data. It looks like a PHP array written with {} and []. JSON is the standard way to pass data between a server and a browser, or in an API, because almost every language can read it.

Array to JSON (encode)

<?php
  $data = [
      "name"  => "Aman",
      "class" => 12,
      "marks" => [90, 85, 88]
  ];
  echo json_encode($data);
?>

json_encode turns the whole array — including the nested marks array — into a single JSON string, ready to send to a browser or API.

JSON to array (decode)

Add true as the second argument to get a PHP array back.

<?php
  $json = '{"name":"Aman","class":12}';
  $arr = json_decode($json, true);
  echo $arr["name"];   // Aman
  echo $arr["class"];  // 12
?>

With true, you access values like a normal associative array ($arr["name"]).

Decode as object

Without true, PHP gives you an object; access with ->.

<?php
  $json = '{"name":"Aman","class":12}';
  $obj = json_decode($json);   // object
  echo $obj->name;             // Aman
?>

Both ways work — choose array style (["name"]) or object style (->name) based on what your code prefers.

Readable JSON

Use JSON_PRETTY_PRINT to format JSON nicely for humans.

<?php
  $data = ["name" => "Aman", "class" => 12];
  echo json_encode($data, JSON_PRETTY_PRINT);
?>

Pretty print adds indentation, which is great while debugging or saving JSON to a file you may read yourself.

Common mistakes

• Forgetting true in json_decode. Without it you get an object, so $x["key"] fails.
• Invalid JSON. A stray comma or missing quote makes json_decode return null.
• Not checking errors. Use json_last_error_msg() to see why decoding failed.
• Mixing object and array access. Use -> for objects, [] for arrays — not both.

Summary

• JSON is a text format for sending data between systems.
• json_encode turns a PHP array into JSON.
• json_decode($j, true) turns JSON into a PHP array.
• Without true, you get an object (use ->).
• Use JSON_PRETTY_PRINT for readable output.

Next, fetch JSON from other sites with PHP cURL, or build a data API using arrays and PHP REST API.