Array with char-keys

[Charma]

Daniel Keep Wrote:

> 
> 
> Charma wrote:
> > thanks to all..
> > i have tested it...
> > seems to work as long as i am writing into the string, but it somehow looks like it is always overriding the same entry...
> > 
> > i got my class:
> > class VFIentry
> > {
> > 	byte VFSfile;
> > 	uint pos;
> > 	uint size;
> > 	byte flags;
> > }
> > 
> > and later in some code i do this:
> > 
> > VFIentry[char[]] VFIndex; // this is the array
> > 
> > 
> > byte VFSt;
> > char[] namet;
> > while(!index.eof())
> > {
> > 	index.readExact(&VFSt, 1);
> > 	index.readExact(&t, 1);
> 
> From here...
> 
> > 	namet.length = t;
> > 	index.readExact(namet.ptr, t);
> > 	VFIndex[namet] = new VFIentry; // **
> > 	VFIndex[namet].VFSfile = VFSt;
> 
> ...to here is, I think, your problem.
> 
> Strings in D are arrays, and arrays are reference types.  So what's
> happening here is that you're reading in the file's name, storing it
> away... and then *overwriting it* on the next file.
> 
> What you need to do is copy the buffer if you plan on re-using it, or
> simply create a new buffer in the first place.  Since you're actively
> using namet in several places, I'd replace:
> 
>   namet.length = t;
> 
> with:
> 
>   namet = new char[t];
> 
> And it should work from there.
> 	
> > 	index.readExact(&VFIndex[namet].flags, 1);
> > 	index.readExact(&VFIndex[namet].pos, 4);
> > 	index.readExact(&VFIndex[namet].size, 4);
> > 	writefln("file: ", namet, " in VFS-File: ", VFIndex[namet].VFSfile, " pos: ", VFIndex[namet].pos, " size: ", VFIndex[namet].size);			
> > }
> > up to this point it seems to work correctly... i hope it isn't too hard to understans... i am reading a file that has informations about in which vfs (virtual file system) the files are and then the name-length, the name, and other informations...
> > i want to read them all into the array VFIndex so that i can later get the informations with VFIndex["file1.dat"] and VFIndex["file2.dat"] and so on...
> > i think my mistake is at the **-marked line but i am not sure..
> > anyone any idea?!?
> 
> Out of interest, what language(s) are you coming from?
> 
>     -- Daniel
> 
> P.S.  Full disclosure: changing .length *can* give you a new string, but
> only if the new length doesn't fit into the previously allocated
> storage.  So files with the same length or shorter won't get new
> storage.  Ones that are larger *might*.
> 
> -- 
> int getRandomNumber()
> {
>     return 4; // chosen by fair dice roll.
>               // guaranteed to be random.
> }
> 
> http://xkcd.com/
> 
> v2sw5+8Yhw5ln4+5pr6OFPma8u6+7Lw4Tm6+7l6+7D
> i28a2Xs3MSr2e4/6+7t4TNSMb6HTOp5en5g6RAHCP  http://hackerkey.com/


thanks a lot! my problem is solved, but to be honest i am not 100% sure why... 
maybe you could explain that again?!? (sorry about that... english isn't my native language)
What I don't understand is why i still need the old name?! once i have saved it in VFIndex, i can override it, right? it is not needed anymore since it is saved in VFIndex, isn't it?

About language.. i think you want to know what i used before: C++, acoutally i still use C++ sometimes... I started using D 3 days ago and only because my friend is using it and we are on a project together...