Pointer Newbie Question

[habakuk]

Hello Community,

i am a new member. Sry for my bad grammer.

Here is my question:
Why do i get a error message from eclipse when i type in

  int *pointer;
  *pointer = &x;

?
The message is "invalid conversion from int* to int".
I think i understand the message. But when i try it on this way

  int *pointer = &x;

i get no error message.
Why? For me it looks like the same.
Or ist this "int *pointer = &x;" equal to "int *pointer; pointer = &x"?
Thanks for helping!

regards habakuk

[Pindrought]

Both of these examples will use the forward declaration

int * pointer;

You can do

pointer=&x;

This will assign the pointer to point at the x memory address

you can also do

*pointer=x;

This is dereferencing the pointer and placing the value of x into the value being held by what the pointer is pointing to.

[MarciusV]

 int *pointer;
 pointer = &x;

or

 int *pointer = &x;

You get an error because you try to assign the address to the object that your pointer points to (by dereferencing it).

EDIT:

Pindrought beat me to it :)

[habakuk]

But why can i do this int *pointer = &x;?
Is this not the same like "You get an error because you try to assign the address to the object that your pointer points to (by dereferencing it)."?

[long double main]

Nah, you just need to think about it this way:
int* pointer = &x; // Means the same as int *pointer = &x;
Here, you can see that pointer is a pointer to an int variable and we're initializing that pointer to point to the address of x.

[TheIdeasMan]

The * has 2 meanings, in a declaration it is a pointer type:

int* p; // p is a pointer to int

I put the * next to the type, this might be less confusing.

It is also used to dereference a pointer variable (retrieve the value that the pointer points to):

int a = *p; // a is now the same as the value that pointer p points to

To do things in order:

int a = 5;

int* p = &a; // pointer p points to the  address of a

int b = *p; // b is now 5 

Hope that Helps :+)

[habakuk]

THX for all Input!
Before i ask again, I will try to understand.

[habakuk]

Ok. I hope i got it:

int x = 0;
int* pointer;
pointer = &x;

same meaning to

int* pointer = &x;

The * in the second example is for declaration. The value assignment didnt recognize the star.