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8.5 The @ operator

The address operator @ returns the address of a variable, procedure or function. It is used as follows:

_________________________________________________________________________________________________________ Address factor
-- --addressfactor- @ --|---variable reference---------------------------- -|-procedure identi er--| -|--function identi er---| -quali ed method identi er-
___________________________________________________________________

The @ operator returns a typed pointer if the $T switch is on. If the $T switch is o then the address operator returns an untyped pointer, which is assigment compatible with all pointer types. The type of the pointer is ^T, where T is the type of the variable reference. For example, the following will compile

Program tcast;  
{$T-} { @ returns untyped pointer }  
 
Type art = Array[1..100] of byte;  
Var Buffer : longint;  
    PLargeBuffer : ^art;  
 
begin  
 PLargeBuffer := @Buffer;  
end.

Changing the f$T-g to f$T+g will prevent the compiler from compiling this. It will give a type mismatch error. By default, the address operator returns an untyped pointer. Applying the address operator to a function, method, or procedure identier will give a pointer to the entry point of that function. The result is an untyped pointer. By default, the address operator must be used if a value must be assigned to a procedural type variable. This behaviour can be avoided by using the -So or -S2 switches, which result in a more compatible Delphi or Turbo Pascal syntax.

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