Arrays and pointers

[justlearning]

I have a problem that says modify a problem I have already done. but I have to use pointer notation instead of array notation. Could someone explain the difference to me.

[m013690]

to access a member in an array, you would use:

array[ 4 ]

to access the same item with pointer notation you could say:

*( array + 4 )

[tyreld]

Here is an illustrative example.

 
int array[4] = { 0, 1, 2, 3 };
int *array_ptr1, *array_ptr2;
 
// we assign array_ptr1 to the address for the first element.
array_ptr1 = &array[0];  
 
// C provides a shorthand for dealing with arrays. We can write the following
// to accomplish the same task.
array_ptr2 = array;
 
if (array_ptr1 == array_ptr2)
  printf("This will always be true because both pointers contain the same value.\n");
 
// Array indices are just doing pointer arithmetic in the background.
printf("Value at index 2 via array index = %d\n", array[2]);
printf("Value at index 2 via pointer addition = %d\n", *(array_ptr1 + 2));