How do you know the pointer address?

Question

In some of the challenge questions, there are pointer addresses *p=&x.

How can you work out the answer?

Let me find an example!

Answer 1

Hi! Don't confuse the two occurences of "*p" to be the same thing. The line

int *p = &x;

says: Declare a variable p of type (int *), that is, a pointer to an int, and assign to it the address of x.

You could actually write this line like so:

int* p = &x; (space between * and p),

which I think is clearer, but equivalent: p is of type pointer to an int, and it gets the value 'address of x'

Now, in the other line,

cout << *p;

*p means a different thing: the * operator (er.. I think it's called the dereferencing operator or some such) is applied to p, and it returns the contents of the memory location that p is pointing to.

In other words: p contains the address of our int x,
and *p here means the contents of that memory address.

If you wanted to see the contents of the pointer p itself (the address of x), you could write

cout << p;

and get some funny-looking thing like 0x7fff1dd8b88c (the hex addr of x).

Hope this helps! Wait I hope I didn't misunderstand the question :-)

Answer 2

*p refers to the value pointed by pointer p which stores the address of x. This means that pointer p is pointing to x. The final output should be the value of x.

x *= x + 9;

// x becomes 190.

cout << *p;

// prints 190

Answer 3

int x = 10;
int *p = &×;
x* = x+9;

cout << *p;

Answer 4

ok. I have clearly misunderstood something about pointers here! Does &x not give the address of x, rather than the value?