definedkeyword

Preprocessor function to test if a symbol has been defined

Syntax

defined (symbol_name)

Parameters

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 #if (or #elseif).
Similar to #ifdef (or #elseifdef) except it allows more than one check to occur because of its flexibility.

Remarks

Differences from QB

• New to FreeBASIC
  
  

See also

• #define
  
• #macro
  
• #if
  
• #else
  
• #elseif
  
• #elseifdef
  
• #elseifndef
  
• #endif
  
• #ifdef
  
• #ifndef
  
• #undef
  
  

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

Reference

• Documented in KeyPgDefined.html