php Magical Constants(_LINE_,_FILE_,_FUNCTION-,_CLASS_ and _METHOD_)

aimtocode

PHP Constants definition:

  • A constant is a name or an identifier for a simple value.
  • A constant value cannnot change during the execution of he script.
  • By default a constant is case-sensitive.
  • By convention, constant identifiers are always uppercase.
  • A constant name statrs with a letter or underscore, followed by any number of letters, numbers, or underscores.
  • To define a constant, use define() function and retrieve the value of a constant.
  • The function constant() is used to read a constant's value.

  • Syntax:

    Result:

      Welcome
    

    Pre-defined constants

    PHP provides a large number of predefined constants to any script which it runs.

    There are Basically five magical constants that change depending on where they are used.

    Name Description
    __LINE__ Represents current line number where it is used.
    __FILE__ Represents full path and file name of the file. If it is used inside an include, name of included file is returned.
    __FUNCTION__ Represents the function name where it is used. If it is used outside of any function, then it will return blank.
    __CLASS__ Represents the class name where it is used. If it is used outside of any function, then it will return blank.
    __METHOD__ Represents the name of the class method where it is used. The method name is returned as it was declared.

    _LINE_

    The current line number of the file where it is used.

    Example:_LINE_

    Result:

    The Line number : 3
    

    Example:_FILE_

    Represents full path and file name of the file. If it is used inside an include, name of included file is returned.

    Result:

    Your file name :D:\SQLBD\htdocs\php\index.php
    

    Example:_FUNCTION_

    _FUNCTION_ Represents the function name where it is used. If it is used outside of any function, then it will return blank.
    _METHOD_Represents the class name where it is used. If it is used outside of any function, then it will return blank.
    _CLASS_Represents the name of the class method where it is used. The method name is returned as it was declared.

    Result:

      Function of demo class : test
      Method of demo class : demo::testme
      Class : demo
    

aimtocode