Common operations for PHP to process JSON data include: 1. Use json_decode() to convert JSON strings into PHP variables, and you can choose to return objects or arrays, and return null if the format is incorrect; 2. Use json_encode() to convert PHP arrays into JSON strings, and support parameters such as JSON_UNESCAPED_UNICODE to retain Chinese; 3. When reading JSON file or interface data, combine file_get_contents or cURL to obtain the content before parsing; 4. Notes include verifying the legitimacy of JSON format, handling nested structures, case sensitivity and null value Boolean conversion issues. Mastering these can deal with most scenarios.

Processing JSON data is actually quite common in PHP, especially when dealing with front-end or APIs. PHP provides several built-in functions to handle JSON, which can basically meet daily needs.

1. Convert JSON string to PHP variable: json_decode()

This is one of the most commonly used operations. For example, if you get a string of JSON format data from the interface and want to operate it in PHP, you have to use json_decode() to turn it first.

 $json = '{"name":"John", "age":30, "city":"New York"}';
$data = json_decode($json);

At this time, $data is an object, you can use $data->name to access the field.
If you want it to be an array instead of an object, add a parameter:

 $data = json_decode($json, true); // Returns the associative array

In this way, $data['name'] can be used, which is more convenient for those who are used to using arrays.

Note: If the JSON format is incorrect, json_decode() will return null, and you can use json_last_error() to check for errors.

2. Convert PHP data to JSON string: json_encode()

This is often used in reverse, for example, you want to output a JSON format response to the front end.

 $arr = array('name' => 'John', 'age' => 30, 'city' => 'New York');
echo json_encode($arr);

The output result is a standard JSON string:

 {"name":"John","age":30,"city":"New York"}

Sometimes you will find that Chinese is converted to Unicode encoding. If you don’t want this, you can add a parameter:

 echo json_encode($arr, JSON_UNESCAPED_UNICODE);

There are also several commonly used options:

• JSON_NUMERIC_CHECK : Automatically convert numeric strings to numeric types
• JSON_PRETTY_PRINT : Format output, it looks better when debugging

3. Process JSON file or interface data

In actual development, local JSON files are often read or JSON content is obtained from remote interfaces.

Read file example:

 $json = file_get_contents('data.json');
$data = json_decode($json);

Example of debugging interface (use cURL for simplicity):

 $ch = curl_init('https://api.example.com/data');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);

$data = json_decode($response);

If it is a POST request, you may also need to set some additional cURL parameters, such as CURLOPT_POST and CURLOPT_POSTFIELDS .

4. Frequently Asked Questions and Precautions

• Is the JSON format correct?
  If parsing fails, it may be that the input JSON is illegal. The format can be checked using online tools.

• How to deal with nested structures?
  JSON often has nested objects or arrays, and after parsing, it is also nested PHP objects or arrays, so you can access them layer by layer.

• Case sensitivity issues?
  The key of JSON is case sensitive, so $data->Name and $data->name are different.

• Pay attention to the conversion of null and boolean values
  JSON's null and false also have corresponding values in PHP, so don't be confused when judging.

Basically these common operations. PHP is quite convenient to handle JSON. As long as you master json_encode and json_decode, and cooperate with simple IO or network requests, you can handle most scenarios.

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