Pointers in C: when to use the ampersand and the asterisk?

Question

I'm just starting out with pointers, and I'm slightly confused. I know `&` means the address of a variable and that `*` can be used in front of a pointer variable to get the value of the object that is pointed to by the pointer. But things work differently when you're working with arrays, strings or when you're calling functions with a pointer copy of a variable. It's difficult to see a pattern of logic inside all of this.When should I use `&` and `*`?

Answer 1

You are correct: & is the address operator which gives the address of the variable;

* is the dereference operator which gives the value of the variable, pointed

to by the pointer

==================================================================

You can pass the address of the variable to a function. In fact, you do just that when using scanf...

int qty;

float price;

printf(" Please input the price of the item :>");

scanf(" %f ", &y);

printf(" Please input the quantity : how many ??? :>");

scanf(" %d", &qty);

float subtotal = qty * price;

=======================================================

The NAME of the array variable IS, in and of itself, the BASE ADDRESS, or

address of the first element in the array.

So you can pass an array just by passing it's name.

Ex. void printArray ( int count, int * A)

{

for (int iLoop=0; iLoop<count; iLoop++)

{

printf("%d ",A[iLoop]);

}

printf("************\n");

}

then in main()..........

int A[10] = {1,2,3,4,5,6,7,8,9,10};

printArray(10,A);

notice that the function takes as it's argument, an integer containing the # of elements in the array,

and then a pointer to integer which receives the base address of the array

=================================================================

Please come back with more specific questions. I am available for tutoring