On 10/31/07, Joao Morais <[EMAIL PROTECTED]> wrote: > Adrian Maier wrote: > > On 10/31/07, Matt Emson <[EMAIL PROTECTED]> wrote: > >> Adrian Maier wrote: > >>> Hello, > >>> > >>> I'm seeking for advice about which is the best way to hold an array of > >>> class instances > >>> I need to access the elements using its position (like a regular > >>> array) , and also i'd like > >>> the structure to grow when I add more elements > >> TObjectList > > > > I am aware that TObjectList is one of the possible ways. > > But I was hoping to get a better understanding about the purpose of these > > various classes or types of array , and more importantly what are the > > drawbacks . > > > > Is there really no wiki page , tutorial, anything that provides an > > overview of > > the collections and types of arrays that FPC has ? > > You can use dynamic arrays, they work like an ansi string: > > var > VArray: array of TSomeClass; > begin > SetLength(VArray, 10); > // now you have VArray[0] .. VArray[9]; > SetLength(VArray, 20); > // now you have [0] .. [19]; > // Length(VArray) = 20 > // for I := 0 to Pred(Length(VArray)) is a valid statement > > They are reference counted, just like ansi strings, ie don't worry about > memory leakages.
The detail that is not crystal clear to me is : after the first SetLength and i set the first 3 elements , is it *guaranteed* that the second SetLength leaves those first 3 elements untouched ? That's what i meant by "resize" as opposed to "reallocate" . Reallocation could occur in some other place in memory , leading to loosing the original contents. I have actually tested it with a small program, but since i've been able to access indexes way beyond the allocated number of elements before getting the program killed i want to be sure that i understand the proper use of dynamic arrays. Thanks Joao ! -- Adrian Maier _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
