json_last_error

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

json_last_error — Returns the last error occurred

Description

json_last_error(): int

Returns the last error (if any) occurred during the last JSON encoding/decoding, which did not specify JSON_THROW_ON_ERROR.

Parameters

This function has no parameters.

Return Values

Returns an integer, the value can be one of the following constants:

JSON error codes
Constant Meaning Availability
JSON_ERROR_NONE No error has occurred  
JSON_ERROR_DEPTH The maximum stack depth has been exceeded  
JSON_ERROR_STATE_MISMATCH Invalid or malformed JSON  
JSON_ERROR_CTRL_CHAR Control character error, possibly incorrectly encoded  
JSON_ERROR_SYNTAX Syntax error  
JSON_ERROR_UTF8 Malformed UTF-8 characters, possibly incorrectly encoded  
JSON_ERROR_RECURSION One or more recursive references in the value to be encoded  
JSON_ERROR_INF_OR_NAN One or more NAN or INF values in the value to be encoded  
JSON_ERROR_UNSUPPORTED_TYPE A value of a type that cannot be encoded was given  
JSON_ERROR_INVALID_PROPERTY_NAME A property name that cannot be encoded was given  
JSON_ERROR_UTF16 Malformed UTF-16 characters, possibly incorrectly encoded  

Examples

Example #1 json_last_error() example

<?php
// A valid json string
$json[] = '{"Organization": "PHP Documentation Team"}';

// An invalid json string which will cause an syntax
// error, in this case we used ' instead of " for quotation
$json[] = "{'Organization': 'PHP Documentation Team'}";


foreach ($json as $string) {
echo 'Decoding: ' . $string;
json_decode($string);

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

echo PHP_EOL;
}
?>

The above example will output:

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

Example #2 json_last_error() with json_encode()

<?php
// An invalid UTF8 sequence
$text = "\xB1\x31";

$json = json_encode($text);
$error = json_last_error();

var_dump($json, $error === JSON_ERROR_UTF8);
?>

The above example will output:

string(4) "null"
bool(true)

Example #3 json_last_error() and JSON_THROW_ON_ERROR

<?php
// An invalid UTF8 sequence which causes JSON_ERROR_UTF8
json_encode("\xB1\x31");

// The following does not cause a JSON error
json_encode('okay', JSON_THROW_ON_ERROR);

// The global error state has not been changed by the former json_encode()
var_dump(json_last_error() === JSON_ERROR_UTF8);
?>

The above example will output:

bool(true)

See Also