预定义常量

以下常量由本扩展模块定义，因此只有在本扩展模块被编译到 PHP 中，或者在运行时被动态加载后才有效。

The following constants indicate the type of error returned by json_last_error(). They are all available as of PHP 5.3.0.

JSON_ERROR_NONE (integer)

No error has occurred.

JSON_ERROR_DEPTH (integer)

The maximum stack depth has been exceeded.

JSON_ERROR_CTRL_CHAR (integer)

Control character error, possibly incorrectly encoded.

JSON_ERROR_SYNTAX (integer)

Syntax error.