From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: ...
Date:	14 Aug 2000 12:34:17 GMT
Organization:	Aachen University of Technology (RWTH)
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Vermin <ratspl AT hotmail DOT com> wrote:
> but how should I use the array in the procedure??
> Let's say that I wanted to fill it with a byte stream from a file, how would
> I then use it??

> something like:

> void readStream(char fileName[], unsigned char **memPos){
>   ..open file, get length of byte stream etc..
>   *memPos = new (unsigned char)[streamLength];
>   for (int i = 0; i <= streamLength; i++){
>     // I know that I should use only one read for it all, but this is just
> an example...
>     fread(memPos[i], 1, 1, inFile);

No. Make that

	fread ((*memPos)+i, 1, 1, inFile);

I know this syntax looks weird, but it's necessary in C.  'memPos'
itself is a pointer to pointer to char, so '*memPos' is a pointer to
char. This you can then access via the array notation ()[i], or like a
pointer by adding the offset i. Or you may feel more comfortable with
the 'long form' notation:

	fread(&((*memPos)[i]), 1, 1, inFile);

Which can be read as: "the address of element [i] of the array at
address *memPos". 

The "memPos[i]" you wrote would also be a pointer to char, but it
spells out as:

	*(memPos + i)

Note the difference in parentheses between this and the correct code,
above.

In C++, it might be possible to use a reference argument 'unsigned
char * mempos&' or whatever the proper syntax is...

-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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