Thread: Pointer and array help!

I am reading through a C book and I am up to 'pointer equivalency' and I am having trouble with this code snippet:

Code:

int i, array[10];
int *pointer, *intPtr;

pointer = array;
i = 4; 

//I know these two statements do the exact thing
intPtr = &array[ i ];
intPtr = pointer + i;

//I need help with this stuff below
int x;
x = pointer[ i ];
x = *(array+i)
intPtr = &pointer[ i ];
intPtr = array + i;

The book then goes on to say that you can use pointers in these [] and that you can use array variable names as if they where pointers to the first element. I understand what the array variable name and how it points to the first element but I am having trouble understanding this snippet.

x=pointer[i] when output will display the dereferenced value that the pointer "pointer" is pointing to. The pointer points to index four (4) of the array, e.g., array[4], which is uninitialized at this point - there may be garbage in there. Thus, if you set array[i]=some_integer, lets say, for this example, 4 ... then the output will be the integer 4.

x=*(array+i) is an alternative to the above, and will result in the same output.

intPtr = &pointer[i] has to be dereferenced when you go to output the intPtr value, since intPtr points to a memory location, e.g., the memory address of "pointer" at index i, which is 4. So intPtr points to the memory address of what is at array index 4. For instance, to see the value held in memory do the following:

printf("this is the value stored in memory %d\n",*intPtr); //this should display the integer 4 as well.

intPtr = array + i yields the same result the last example, above.