Predefined preprocessor constants

MQL5 has several predefined constants that are equivalent to simple macros, but they are defined by the compiler itself. The following table lists some of their names and meanings.

Name	Description
__COUNTER__	Counter (each mention in the text during macro expansion results in an increase of 1)
__DATE__	Compilation date (day)
__DATETIME__	Compilation date and time
__FILE__	The name of the compiled file
__FUNCSIG__	Current function signature
__FUNCTION__	Current function name
__LINE__	Line number in the compiled file
__MQLBUILD__, __MQL5BUILD__	Compiler version
__RANDOM__	Random number of type ulong
__PATH__	Path to compiled file
_DEBUG	Defined when compiling in debug mode
_RELEASE	Defined when compiling in normal mode

Cancelling macro substitution (#undef)

Conditional compilation (#ifdef/#ifndef/#else/#endif)