🚀 go-pugleaf

x1e1r1@concentric.net wrote:
: I must have missed something.  What exactly do the extra  *'s in front of a
: pointer mean?  There were a few test questions about memory addresses that
: had these( int  ***Q for example).  Anyone?

Something that looks like T* is "pointer to T", for any T.  Hence, an
int*** is a pointer to pointer to pointer to int.

A C-ism carried over into C++ is that you often can't tell, when given
a T*, whether this is an array of T or a single T passed by address:

   void print_ints(int n, int* arr) {
     // int arr[n]
     for (int i = 0; i < n; i++)
       cout << arr[i] << " ";
     cout << endl;
   }

   void get_length(char* str, int* len) {
     // return len of str in len
     *len = 0;
     if (str != 0)
       while (*str) {
         str++;
	 (*len)++;
       }
   }

In print_ints, the int* is an array.  In get_length, the int* is an
"output" parameter.

It's common to see, for example, an int**.  This is often an array of
ints passed by address:

    void get_array(int len, int** arr) {
      *arr = new int[len];
    }

More than two '*'s is pretty infrequent.

    Ken Shrum

In article <6vk3sl$mie@journal.concentric.net>,
  <x1e1r1@concentric.net> wrote:
> I must have missed something.  What exactly do the extra  *'s in front of a
> pointer mean?  There were a few test questions about memory addresses that
> had these( int  ***Q for example).  Anyone?
>

Each * represents a pointer to something.  So int ** means a pointer to a
pointer to an int.

Remember a pointer is actually an address in memory of some variable. So a
pointer to a pointer is the address of a pointer variable, which contains an
address to another variable.

You can thus have pointers to pointers to pointers ... and so on.

A very common use of pointers to pointers is in the passing of command line
arguments to a main function in C/C++ (I won't go into it here).

Chris

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