Unterminated string constants Several commonly used magic constants in PHP

There are seven magic constants whose values ​​change depending on their location in the code. For example, the value of __LINE__ depends on the line it is in the script. These special constants are not case-sensitive, as follows:

Name	Description
__LINE__	The current line number in the file.
__FILE__	The full path and file name of the file. If used within an included file, returns the name of the included file. Since PHP 4.0.2, __FILE__ always contains an absolute path (or the resolved absolute path in the case of a symbolic link), while versions before that sometimes contained a relative path.
__DIR__	The directory where the file is located. If used within an included file, returns the directory where the included file is located. It is equivalent to dirname(__FILE__). Directory names do not include the trailing slash unless they are the root directory. (New in PHP 5.3.0) =
__FUNCTION__	Function name (New in PHP 4.3.0). Since PHP 5 this constant returns the name of the function as it was defined (case sensitive). In PHP 4 this value is always lowercase.
__CLASS__	The name of the class (new in PHP 4.3.0). Since PHP 5 this constant returns the name of the class when it was defined (case sensitive). In PHP 4 this value is always lowercase.
__METHOD__	The method name of the class (newly added in PHP 5.0.0). Returns the name of the method as it was defined (case-sensitive).
__NAMESPACE__	The name of the current namespace (case sensitive). This constant is defined at compile time (new in PHP 5.3.0)

The above has introduced several commonly used magic constants in PHP, including unterminated string constants. I hope it will be helpful to friends who are interested in PHP tutorials.