Common problems and solutions for PHP to deal with JSON encoding include: 1. Chinese characters are escaped and Chinese is retained using JSON_UNESCAPED_UNICODE; 2. When the array key is discontinuous, it can be controlled by JSON_FORCE_OBJECT; 3. Floating point numbers retain decimal 0, using JSON_PRESERVE_ZERO_FRACTION; 4. Error handling is checked by json_last_error(). In actual applications, you need to pay attention to object properties, resource types, circular references and recursive depth. Setting parameters reasonably can ensure the correctness of encoding.

When dealing with JSON encoding in PHP, many people will encounter some common problems, such as garbled Chinese code, incorrect format, or incorrect data type conversion. PHP provides the json_encode() function to convert variables to JSON format, but in actual use, some details and parameter settings need to be paid attention to.

1. Basic usage method

json_encode() is the most commonly used JSON encoding function in PHP. Its basic syntax is:

 json_encode($value, $options = 0, $depth = 512);

• $value : The variable to encode, usually an array or object.
• $options : Optional parameter to control encoding behavior, such as JSON_UNESCAPED_UNICODE can retain Chinese characters.
• $depth : Specifies the recursive depth, the default is 512.

Example:

 $data = array('name' => 'Zhang San', 'age' => 25);
echo json_encode($data);

The default output will be:

 {"name":"\u5f20\u4e09","age":25}

If you want Chinese characters not to be escaped, you can add JSON_UNESCAPED_UNICODE :

 echo json_encode($data, JSON_UNESCAPED_UNICODE);

Output result:

 {"name":"Zhang San","age":25}

2. FAQs and solutions

When using json_encode() , you often encounter some problems. The following are several common problems and corresponding solutions:

• Chinese characters are escaped : Use the JSON_UNESCAPED_UNICODE parameter.
• Array becomes an object : If the key of the array is not a continuous numeric index, json_encode() will convert it into an object. If you want to force the array format, you can use JSON_FORCE_OBJECT .
• Floating point accuracy problem : Use JSON_PRESERVE_ZERO_FRACTION to retain 0 after the decimal point.
• Error handling : Use json_last_error() to check whether there is an error, such as:

 $json = json_encode($data);
if ($json === false) {
    echo json_last_error_msg();
}

3. Practical application scenarios

When developing API interfaces, json_encode() is the standard way to return data. For example, build a simple API response:

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

$response = array(
    'status' => 'success',
    'data' => array('id' => 1, 'name' => 'Zhang San')
);

echo json_encode($response, JSON_UNESCAPED_UNICODE);

The JSON data returned in this way not only maintains Chinese readability, but also conforms to the standard format.

In addition, if the data you fetch from the database contains special characters (such as double quotes), you can also use htmlspecialchars() or addslashes() to avoid JSON format errors.

4. Tips and precautions

• If you pass in an object, the object's public properties will be converted to JSON by default, and private and protected properties will not be included.
• If you want to customize the JSON output of the object, you can implement the JsonSerializable interface in the class.
• If the data contains resource type (resource) or has a circular reference, json_encode() will report an error or return null , and it needs to be processed in advance.
• When nesting multi-layer arrays or objects, it is recommended to set appropriate $depth parameters to avoid exceeding the recursive limit.

Basically that's it. The key to using json_encode() well is to understand the parameters and data structures, and don't let the default behavior "scam" you.

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