What are the common methods of php json

php Common json methods: 1. json_encode(), used to decode strings in JSON format; 2. json_encode(), used to decode strings in JSON format; 3. json_last_error() , used to return the last error that occurred.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

php json common methods :

1. json_encode()

PHP json_encode() is used to JSON encode variables. This function returns JSON data if executed successfully. , otherwise return FALSE.

Syntax

string json_encode ( $value [, $options = 0 ] )

Example:

<?php
   $arr = array(&#39;a&#39; => 1, &#39;b&#39; => 2, &#39;c&#39; => 3, &#39;d&#39; => 4, &#39;e&#39; => 5);
   echo json_encode($arr);
?>

Output result:

{"a":1,"b":2,"c":3,"d":4,"e":5}

2, json_encode()

json_decode() function is used to decode JSON format strings and convert them into PHP variables.

Syntax:

mixed json_decode ($json_string [,$assoc = false [, $depth = 512 [, $options = 0 ]]])

Parameters:

• json_string: JSON string to be decoded, must be UTF-8 encoded data

• assoc: When this parameter is TRUE, an array will be returned, and when FALSE, an object will be returned.

• depth: Integer type parameter, which specifies the recursion depth

• options: Binary mask, currently only JSON_BIGINT_AS_STRING is supported.

Example:

Output result:

object(stdClass)#1 (5) {
    ["a"] => int(1)
    ["b"] => int(2)
    ["c"] => int(3)
    ["d"] => int(4)
    ["e"] => int(5)
}

array(5) {
    ["a"] => int(1)
    ["b"] => int(2)
    ["c"] => int(3)
    ["d"] => int(4)
    ["e"] => int(5)
}

3, json_last_error()

json_last_error — Return the last error that occurred

Syntax:

json_last_error()

If any, return the last error that occurred during JSON encoding and decoding. An integer will be returned, and this value will be one of the following constants:

No error occurred##JSON_ERROR_STATE_MISMATCHJSON_ERROR_CTRL_CHARJSON_ERROR_SYNTAX##JSON_ERROR_UTF8JSON_ERROR_RECURSIONJSON_ERROR_INF_OR_NAN##JSON_ERROR_UNSUPPORTED_TYPEJSON_ERROR_INVALID_PROPERTY_NAMEJSON_ERROR_UTF16

<?php
// 一个有效的 json 字符串
$json[] = &#39;{"Organization": "PHP Documentation Team"}&#39;;

// 一个无效的 json 字符串会导致一个语法错误，在这个例子里我们使用 &#39; 代替了 " 作为引号
$json[] = "{&#39;Organization&#39;: &#39;PHP Documentation Team&#39;}";


foreach ($json as $string) {
    echo &#39;Decoding: &#39; . $string;
    json_decode($string);

    switch (json_last_error()) {
        case JSON_ERROR_NONE:
            echo &#39; - No errors&#39;;
        break;
        case JSON_ERROR_DEPTH:
            echo &#39; - Maximum stack depth exceeded&#39;;
        break;
        case JSON_ERROR_STATE_MISMATCH:
            echo &#39; - Underflow or the modes mismatch&#39;;
        break;
        case JSON_ERROR_CTRL_CHAR:
            echo &#39; - Unexpected control character found&#39;;
        break;
        case JSON_ERROR_SYNTAX:
            echo &#39; - Syntax error, malformed JSON&#39;;
        break;
        case JSON_ERROR_UTF8:
            echo &#39; - Malformed UTF-8 characters, possibly incorrectly encoded&#39;;
        break;
        default:
            echo &#39; - Unknown error&#39;;
        break;
    }

    echo PHP_EOL;
}
?>

Output result:

JSON error code

Constant	Meaning	Availability
##JSON_ERROR_NONE
##JSON_ERROR_DEPTHMaximum stack depth reached
Invalid or abnormal JSON
The control character is wrong, maybe the encoding is wrong
Syntax error
Exceptional UTF-8 characters, perhaps due to incorrect encoding. PHP 5.3.3
One or more recursive references in the value to be encodedPHP 5.5.0
One or more NAN	or INF values ​​in the value to be encodedPHP 5.5.0
specified Type, value cannot be encoded. PHP 5.5.0
The specified property name cannot be encoded. PHP 7.0.0
Malformed UTF-16 characters, possibly because The character encoding is incorrect. PHP 7.0.0		Example:

Decoding: {"Organization": "PHP Documentation Team"} - No errors
Decoding: {'Organization': 'PHP Documentation Team'} - Syntax error, malformed JSON

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