Thread: pointers

Originally Posted by bazzano

Hey guys if i declare

Code:

int *px;

does that mean px is a pointer to an int

Yes.

Originally Posted by bazzano

Code:

float *pa = &a;

would that mean the address of &a is of pa which is a pointer to the float

If a is a float, then &a is the address of the float a, and in the initialization the float pointer pa would have a value of the address of a.

Originally Posted by bazzano

how about if its this

double *a[12] would that be a pointer to a pointer of type double because its an array

a is an array of 12 pointers to double. a[0], a[1], etc. is each a pointer to double.

A pointer to a pointer to a double is declared as double **a.

In general, the type is best understood by reading it from right to left:
[12] an array of twelve <- * pointers <- double to doubles.

I've come to think of it as kind of a spiral from the middle.
http://www.codeproject.com/cpp/compl...ight_left_rule

Originally Posted by bazzano

So if i have

Code:

int [5] = {10,20,30,40,50}

if i say

Code:

(x + 2)

would that give me 30

and if i go

Code:

(*x + 2)

will that make x point to the address of 30

but also how about if it was

Code:

*(x + 2)

If you have

Code:

int x[5] = {10,20,30,40,50}

then

Code:

(x + 2)

is the address of the int containing 30.

If you have

Code:

(*x + 2)

that would be a value of 12.

If you have

Code:

*(x + 2)

that would be the value 30.

Perhaps your compiler could.

Code:

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
   int x[5] = {10,20,30,40,50};
   int *y = (x + 2);
   int z = (*x + 2);
   int p = *(x + 2);
   printf(" y = &#37;p\n", (void*)y);
   printf("*y = %d\n", *y);
   printf(" z = %d\n",  z);
   printf(" p = %d\n",  p);
   return 0;
}

Sometimes you just need to look at something a couple hundred times before it is as clear as can be.

I know I have. And there are still more than a few things on the list.

Originally Posted by bazzano

What i dont get is how you got 12 for Z

*x is 10
10 + 2 is 12

Originally Posted by bazzano

So does that int z = (*x+2)

x is alread pointing to the zeroth element in the array but because its a * its getting the value of x which is 10. Then adding 2 to ten.

And not incrementing where x is pointing too

yes...