How data types are mapped from the PHP variable to the JSON text string when calling the json_encode() function?

Data types are mapped from the PHP variable to the JSON text string based on the following table, when calling the json_encode() function:

PHP Data Type     >  JSON Data Type
-------------     >  -------------
null              >  null
Boolean           >  Boolean
Int or Float      >  Number
String            >  String
Array             >  Array
Object            >  Object
Associative Array >  Object

Here is a PHP example that shows you how json_encode() maps PHP data types to JSON data types:

<?php
# json_encode_datatype.php
# Copyright (c) FYIcenter.com 

   $var = null;
   print("\nInput: ");
   var_dump($var);
   print("Output: ".json_encode($var)."\n");

   $var = true;
   print("\nInput: ");
   var_dump($var);
   print("Output: ".json_encode($var)."\n");

   $var = 20.20;
   print("\nInput: ");
   var_dump($var);
   print("Output: ".json_encode($var)."\n");

   $var = 2020;
   print("\nInput: ");
   var_dump($var);
   print("Output: ".json_encode($var)."\n");

   $var = "2020";
   print("\nInput: ");
   var_dump($var);
   print("Output: ".json_encode($var)."\n");

   $var = array("a","b","c");
   print("\nInput: ");
   var_dump($var);
   print("Output: ".json_encode($var)."\n");

   $var = new stdClass();
   $var->a = "1";
   $var->b = "2";
   $var->c = "3";
   print("\nInput: ");
   var_dump($var);
   print("Output: ".json_encode($var)."\n");
?>

If you run the above PHP code through the PHP engine, you get the following output:

>\fyicenter\php\php.exe json_encode_datatype.php

Input: NULL
Output: null

Input: bool(true)
Output: true

Input: float(20.2)
Output: 20.2

Input: int(2020)
Output: 2020

Input: string(4) "2020"
Output: "2020"

Input: array(3) {
  [0]=>
  string(1) "a"
  [1]=>
  string(1) "b"
  [2]=>
  string(1) "c"
}
Output: ["a","b","c"]

Input: object(stdClass)#1 (3) {
  ["a"]=>
  string(1) "1"
  ["b"]=>
  string(1) "2"
  ["c"]=>
  string(1) "3"
}
Output: {"a":"1","b":"2","c":"3"}

⇒ json_encode() - PHP Associative Array to JSON Object

⇐ json_encode() Function in PHP

⇑ Using JSON in PHP

⇑⇑ JSON Tutorials