Thread: Pointer question

Sounds simple... but why isn't bookPtr = &theBook the same as
*bookPtr =theBook?

I dont think so these statements are same
because first case is correct you are giving address to the pointer but second case is not correct actually.

Code:

bookPtr = &theBook

This makes only sense if bookPtr was declared as a pointer:

Code:

char * bookPtr;

or

id * bookPtr;

The first example declares a pointer that can hold the address of a char (otherwise said: a pointer to char). The second variant is the declaration of a pointer to int. Thus the asterisk * is used here to declare a pointer.
These statements just declare bookPtr as a variable that can hold an address. Let's assume that you declared it as a pointer to id. Then

Code:

int theBook = 67;
bookPtr = &theBook

declares theBook as an int and stores the value 67 in it. The second line makes bookPtr point to the address of theBook.
Now, the second statement:

Code:

*bookPtr =theOtherBook

Here the asterisk is used as a "derefence operator", meaning "the variable where bookPtr points to". We gave it the address of theBook in the previous code-block. Now we are giving this variable (theBook) the value of another variable: theOtherBook.

So, we changed he value of theBook in an indirect way, namely via its pointer. The dereference operator * is therefore also called "indirection operator".