🚀 go-pugleaf

"Maurice Anderson" <mauriceanderson@hotmail.com> wrote:

>What is char**.   I know char* is a pointer but what is the extra "*" for?

It's a pointer to a pointer.

For example:

  void
  set_text(char ** text)
  {
     *text = "Hello world";
  }

'text' here is a pointer to a pointer. This means that you have to use
'*' on the variable to get back to the original pointer type.

And what do you use it for? Well, you can pass a pointer to this
function by reference, and the function will update it:

  char* text = NULL;
  set_text(&text);
  puts(text);  // prints out 'Hello world'
  
In terms of your original question, you've probably got something like:

  void
  set_text(BSTR* text)
  {
     *text = ::SysAllocString(L"Hello world");
  }

Note the common pattern:

  SomeType data;
  set(&data);
      |
      `-------.
              |
  void        |
  set(SomeType* data)
  {           |
     ,--------'
     |
     *data = ...;
  }


Alan Bellingham
-- 
alanb@episys.com