Beam me up Scotty, multiple times!!!
The question might come up, "How can I get a pointer
to point to a pointer?" Ok, maybe this question won't come up in
your mind, but it might come up in your programming. I just want to
touch on the subject on how to do it.
First let's look at some code:
int melissa = 5;
paul = &melissa;
ramon = &paul;
printf("ramon = %d\n", ramon);
printf("&paul = %d\n", &paul);
printf("*ramon = %d\n", *ramon);
printf("&melissa = %d\n", &melissa);
printf("**ramon = %d\n", **ramon);
Let's take this line by line. The first line declares
a double pointer called ramon. We then declare a pointer called
paul. And finally we declare a regular integer called melissa
which we initialize to 5.
Next, we point paul to melissa, which stores
melissa's address into paul's house. Then we point ramon
to paul, which will store paul's address into ramon's
So, now let's look at what will be printed out using the
diagram below's addresses.
ramon = 1000
&paul = 1000
*ramon = 500
&melissa = 500
**ramon = 5
Well the first printout is pretty simple. What is stored
in ramon's house which is the address of paul's house.
We check that with the second printout. Then we printout the value of
what ramon is pointing to. This would be melissa's address
since that is what paul is storing. We check this with the fourth
line of code. Now, the final line is the tricky part. It simply asks,
"Whatever is the value that ramon is pointing to, take that
value and see what is the value that it is pointing to." If that
made no sense at all, another way to think of it is breaking it up.
Take the value of what ramon is pointing to, 500.
Now take 500 and see what is stored in that address, 5. See, it is that
easy. Ok, well, maybe the picture below will help you out.
The best way to learn this stuff is just doing some programming
examples on your own and see what comes out.
Hope you had fun learning this material as I have had
making it. Make sure you take the QUIZ for REAL Dummies to see if you
learned anything. Take care.