defined

Preprocessor function to test if a symbol has been defined

Syntax
	defined (symbol_name)

Parameters
	symbol_name
		Name of the symbol to test

Return Value
	Returns non-zero (-1) if the symbol has been defined, otherwise returns 
	zero (0).

Description
	Given the symbol name, the defined() preprocessor function returns true 
	if the symbol has been defined - or false if the symbol is unknown.

	This is used mainly with KeyPgPpif#if (or KeyPgPpelseif#elseif).
	Similar to KeyPgPpifdef#ifdef (or KeyPgPpelseifdef#elseifdef) except it allows more than one check 
	to occur because of its flexibility.

Example
	'e.g. - which symbols are defined out of a, b, c, and d ?

	Const a = 300
	#define b 12
	Dim c As Single

	#if defined(a)
	 Print "a is defined"
	#endif
	#if defined(b)
	 Print "b is defined"
	#endif
	#if defined(c)
	 Print "c is defined"
	#endif
	#if defined(d)
	 Print "d is defined"
	#endif

Differences from QB
	* New to FreeBASIC

See also
	* KeyPgPpdefine#define
	* KeyPgPpmacro#macro
	* KeyPgPpif#if
	* KeyPgPpelse#else 
	* KeyPgPpelseif#elseif 
	* KeyPgPpelseifdef#elseifdef 
	* KeyPgPpelseifndef#elseifndef 
	* KeyPgPpendif#endif 
	* KeyPgPpifdef#ifdef
	* KeyPgPpifndef#ifndef
	* KeyPgPpundef#undef

