Data types

• Generic Pointer: There is no built-in untyped Pointer in GNU Pascal. Use `^Void' to define it.
• Integer types: There is no built-in Byte, Word, etc. in GNU Pascal. Use the modifiers `__byte__', `__short__', `__long__' and `__unsigned__' (described in See section GNU Pascal extensions) to define them.

    Borland Pascal          GNU Pascal
  
    shortint                __byte__ Integer
    Integer                 __short__ Integer
    LongInt                 Integer = __long__ Integer
    Comp                    __longlong__ Integer
    Byte                    __unsigned__ __byte__ Integer
    Word                    __unsigned__ __short__ Integer
      -                     __unsigned__ __long__ Integer
      -                     __unsigned__ __longlong__ Integer
  

  Real types: There is no built-in `Single', `Double', `Extended' in GNU Pascal; Real has 8 bytes on an Intel-x86 machine. Use `__short__ Real' to define `Single', `__long__ Real' to define `Extended'.

    Borland Pascal          GNU Pascal
  
    Single                  __short__ Real
    Real                      -
    Double                  Real
    Extended                __long__ Real
    Comp                    __longlong__ Integer
  

  A KNOWN BUG: You cannot writeln variables of a type with a __ modifier. To work around, cast them to their basis type (Integer or Real) when writelning them:

    Var
      x: __long__ Real;
  
    writeln ( Real ( x ) );
  

• Complex numbers: According to Extended Pascal, GNU Pascal has built-in complex numbers.
• Record types: GNU Pascal alignes 32-bit fields on 4-byte addresses. Thus the record

    Type
      myRec = record
        f, o, oo: Boolean;
        Bar: Integer;
      end (* myRec *);
  

  has 8 bytes, not 7.
• Instead of procedural types, GNU Pascal has pointers to procedures:

      Type
        FuncPtr = ^Function ( Real ): Real;
  

  Furthermore, GNU Pascal supports Standard Pascal's procedural parameters--see below.