@

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@

The address operator @ returns the address of a variable, procedure or function.

Normally, the value @ returns is an untyped pointer. If you are handling pointers a lot, and want to mitigate issues with passing references of wrong type's target, you have use the directive {$typedaddress on}.

Here some example to demonstrate, what produces with untyped pointers valid and functional code, but semantically outputs an erroneous result:

program typedAddress(input, output, stderr);

procedure incrementIntByRef(const ref: PByte);
begin
	inc(ref^);
end;

var
	foo: integer;
begin
	foo := -1;
	incrementIntByRef(@foo);
	writeLn(foo);
end.

It should print 0 (zero), but prints -256. With {$typedaddress on} compilation fails with an incompatible type error. You usually want the latter behavior (compile-time failure) instead of wasting time with hours of debugging.

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• The @ operator
• Typed address operator (@)