Ajax Learning--The ideal data exchange language JSON

First, the syntax structure of JSON

1. Basic structure

1> a collection of name/value pairs (objects, records, structures, dictionaries, hash tables ...)

A name/value pair is an element, the element name and value are separated by the " : " number, and multiple name/value pairs are combined into a JSON structure, and the name/value pairs are separated by " , ".

Example: JSON structure:

{     "name":  "AJAX",     "sex": "Man"}

2> sequence Table (array) of values

Example:

["AJAX", "HTML", "PHP"]

2. Brace save object, square brackets Save array

3. Objects can hold multiple name/value pairs, and arrays can hold multiple objects

Example:

{"   student": [          {"Name": "Charles", "id": "123"},          {"Lesson": "Math", "Teacher": "Tom"},          {"Address": " AAA "," Number ":" 1 "}]}

Ii. types of values in JSON

1. Object 2. Array 3. Number 4. String 5. Boolean value 6.null

Third, the language support of JSON

There are many languages that support JSON: Javascript, PHP, C #, C, C + +, Java ...

1.JSON is based on JavaScript, so the basic structure of JavaScript native support for Json,json is actually the object and data in JavaScript,

With the function--eval (string) in JavaScript, you can convert the JSON data to a JavaScript object.

Example:

var obj =eval ("(" + Json_txt + ")");

Note: The text must be wrapped in parentheses to avoid errors.

The 2.PHP uses Json,json to support JSON from version 5.2, implemented by Json_encode () and Jsno_decode () two methods.

Example:

Suppose $book is an example of an array, a number, and so on, converting $book to JSON format:

$json      

Json_decode () Converts the JSON to a PHP object.

Iv. advantages and disadvantages of JSON

1. Advantages:

1>json is simpler than XML

2> Easy to parse

3> Simple Structure

2. Disadvantages:

There is no namespace mechanism like XML

Ajax Learning--The ideal data exchange language JSON