On Sun, Feb 9, 2014 at 12:34 PM, Jürgen Hestermann <juergen.hesterm...@gmx.de> wrote: > (...) > With the following declaration and code: > > ------------------- > var A,B: array of integer; > ... > SetLength(A,10); > B := A; > SetLength(B,20); > ------------------- > > both variables A and B point to the same array with 20 Elements. > Changing A changes B and vice versa. > But a slight modification > > ------------------- > SetLength(A,0); > B := A; > SetLength(B,20); > ------------------- > > makes both variables A and B totaly decoupled! Although B is still assigned > to be the same as A each variable is now a separate array with individual > lengths and elements. Variable A has the length 0 and variable B is of > length 20. Changing the length for one of them does no longer change the > length of the other. If someone thinks about dynamic arrays as black boxes > without the need to know the details because they are handled in the > background then he will certainly be baffled by this. > (...)
In other words: dynamic arrays are like AnsiStrings without the copy-on-write semantics. I'd certainly wish Borland copied the COW semantics :-/ -Flávio _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
