Pointers

[The Hobo]

Where can I find a good site about pointers? Documentation, tutorials, explainations, etc?

[The Hobo]

Okay. I have a basic understanding of what they do.

I'm just confused as to why?

Can anyone give me a practical example of using pointers?

[parksie]

Do a search round the forum, I explained this in detail a few months back

Here's one use:

bool get_number(int key, int *target) {
    if(key > 20)
        return false;

    *target = raw_lookup(key);
    return true;
}

...or something. Bit contrived, but it's a way of returning more than one value from a function. They have far more uses though...

[Zaffir]

As far as i understand them, they let you play with variables that dont' belong to the function you're in.

But i'm a complete newb, so take what i say with a grain of salt.

[The Hobo]

What's the difference between that and references then? like:

void myFunction(int &bing)

[CornedBee]

In this case references are C++'s answer to the problem pointers caused: bad pointers, ugly and hard-to-read syntax.

references don't exist in C, so in C++ always use references unless you have a damn good reason to use pointers.

There are many other uses to pointers, the most common are traversing arrays (including char arrays) and dynamic memory allocation.
And a reference cannot be set to NULL, which sometimes can cause problems.

[The Hobo]

hmm...

I don't know why I find them so confusing, but I still don't have a damn clue.

I'll just have to wait until they're covered in one of my classes.

Thanks for your help!

[transcendental]

Here's a link

http://pweb.netcom.com/~tjensen/ptr/pointers.htm

[jim mcnamara]

suppose you want the length of a null-terminated char array:

This says: step thru each character, keep going as long as the char is not a zero. increment a counter for each non-zero char.

for(char *buf=somestring,int len=0;*buf;len++,buf++);

At loop exit, len equals the number of characters.

This is essentially what strlen() does.

[CornedBee]

Except that strlen will not increment a counter, but rather use pointer arithmetic:

size_t __cdecl strlen(const char* str) {
  const char *run;
  for(run=str;*run;++run);
  return run - str;
}