On Mon, 18 Mar 2024, Hairy Pixels via fpc-pascal wrote:
Curious, why did the address of "s" change here? Shouldn't the AnsiString be
incrementing a reference count and not actually changing the actual pointer or copying?
Correct me if I'm wrong, AnsiString is ref counted when passing in/out
functions but copies on assignment so technically no two AnsiStrings can be
shared in two locations, which makes sense because if they were resized they
would invalidate each others memory anyways when ReAllocMem is called.
I guess if that's true then there must be only pointer to any AnsiString in any
given scope otherwise they could resize and corrupt their memory.
Not sure if that makes sense, I'm struggling to understand myself. :)
============================================
procedure PassString(s: AnsiString);
begin
writeln(hexstr(@s));
end;
var
s1: AnsiString;
begin
s1 := '123';
writeln(hexstr(@s1));
PassString(s1);
writeln(hexstr(@s1));
end.
Output:
000000010259AC00
000000016DBC2F80
000000010259AC00
An ansistring is a pointer to a memory block.
You are printing the address of S1 and the address of S, i.e. the address of
the pointer itself, not the address of what S (or s1) points to.
Obviously the address of the s is different of s1.
What you want to do is print hexstr(pointer(s))
if you do that, you'll have the same output 3 times.
Michael.
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