How to convert json data to array in php

In Web development, JSON technology has become an indispensable part and is widely used in front-end and back-end data transmission and storage. In PHP language, we often need to convert JSON data into arrays for operation and processing. This article will introduce you to how to convert JSON into an array.

1. Use the json_decode() function

In PHP, we can use the built-in function json_decode() to parse a JSON string into a PHP array. The basic usage of this function is as follows:

mixed json_decode ( string $json [, bool $assoc = false [, int $depth = 512 [, int $options = 0 ]]] )

Among them, the parameter $json represents the JSON string to be parsed, $assoc represents whether to convert the parsed object into an array with key names, the default is false, $depth Represents the depth of parsing, the default is 512, $options represents parsing options, the default is 0.

For example, we have the following JSON string:

{"name": "Tom", "age": 18, "hobbies": ["music", "movies"]}

We can convert it into an array through the following PHP code:

$json = '{"name": "Tom", "age": 18, "hobbies": ["music", "movies"]}';
$arr = json_decode($json, true);
print_r($arr);

The output result is as follows:

Array
(
    [name] => Tom
    [age] => 18
    [hobbies] => Array
        (
            [0] => music
            [1] => movies
        )

)

2. Dealing with common problems in conversion

In actual applications, we may encounter the problem that some JSON strings cannot be correctly converted into arrays. Next, we will introduce some common problems and its solution.

1. The JSON string contains special characters

For example, when the JSON string contains special characters such as single quotes or double quotes, the program will report an error or the conversion will fail. Case. At this time, we can avoid this situation by escaping the string. PHP provides a built-in function addslashes() for escaping.

For example:

$json = '{"name": "Tom\'s book", "page": "100\""}';
$json = addslashes($json);
$arr = json_decode($json, true);
print_r($arr);

The output result is as follows:

Array
(
    [name] => Tom's book
    [page] => 100"
)

2. The JSON string contains Chinese

When the JSON string contains In Chinese, if no processing is done, it will cause conversion failure or garbled characters. PHP provides a built-in function json_encode() to convert an array into a JSON string, and parameters can be set to avoid Chinese garbled characters.

For example:

$arr = array('name' => '张三', 'age' => 19);
$json = json_encode($arr, JSON_UNESCAPED_UNICODE);
echo $json;

The program will output the following results:

{"name":"张三","age":19}

When performing reverse processing, you need to use a JSON string in UTF-8 encoding format, otherwise the same There will be garbled code problems.

3. JSON string format error

When the JSON string format is incorrect, the json_decode() function will not be able to parse the string correctly. At this time, we need to first perform format verification on the JSON string, and then correct it according to different error types.

For example:

$json = '[{"name": "Tom", "age": 18}, {"name": "Bob", "age":19}';
$arr = json_decode($json, true);
if (json_last_error() !== JSON_ERROR_NONE) {
    switch (json_last_error()) {
        case JSON_ERROR_DEPTH:
            echo 'JSON字符串超出最大剖析深度';
            break;
        case JSON_ERROR_STATE_MISMATCH:
            echo 'JSON字符串格式错误';
            break;
        case JSON_ERROR_UTF8:
            echo 'JSON字符串包含非UTF-8字符';
            break;
        default:
            echo 'JSON字符串解析失败';
            break;
    }
} else {
    print_r($arr);
}

The output result is as follows:

JSON字符串格式错误

The above is the method to convert JSON into an array and the solutions to various problems. I hope this article can be helpful to PHP developers.

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