defined
Preprocessor function to test if a symbol has been defined
defined (symbol_name)
symbol_name
Returns non-zero (-1) if the symbol has been defined, otherwise returns zero (0).
Given the symbol name, the defined() preprocessor function returns true if the symbol has been defined - or false if the symbol is unknown of.
This is used mainly with #if.
Similar to #ifdef except it allows more than one check to occur because of its flexibility.
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 of.
This is used mainly with #if.
Similar to #ifdef 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
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
