1. CS148 Introduction to Programming II
Ayman Abdel-Hamid
Department of Computer Science
Old Dominion University
Lecture 9: 2/14/2003
Lecture 9: 2/14/2003
CS148 Spring 2003

2. Outline What is a pointer data type? Operations on pointers
Lecture 9: 2/14/2003
CS148 Spring 2003

3. What is a pointer data type?
A pointer is a built-in data type (like any other data types, e.g., int, float)
A pointer is a reference data type. A pointer variable contains the memory address (location) of another variable
5008
Address
Variable Name
5000
intPtr
beta
Memory
intPtr
beta
Abstract Diagram
Lecture 9: 2/14/2003
CS148 Spring 2003

4. Pointer Variables and Operations
Pointer Variable Declaration
DataType* Variable;
DataType* Variable, *Variable…;
Example
int* intPtr;
//intPtr contains the address of an int variable
Pitfall
int* p, q; //q here is of type int and not int*
Never use a pointer before initializing it
Lecture 9: 2/14/2003
CS148 Spring 2003

5. Pointer Variables and Operations
address-of operator (&)
int beta;
int* intPtr;
intPtr = β
//separate initialization: memory address of beta is stored into intPtr.
Or alternatively
int* inPtr = β //initialization with declaration
Lecture 9: 2/14/2003
CS148 Spring 2003

6. Pointer Variables and Operations
dereference operator (*)
int beta;
int* intPtr = β
*intPtr = 28;
//dereference intPtr and store value 28 into beta. Indirect Addressing of beta 28
intPtr
beta
Lecture 9: 2/14/2003
CS148 Spring 2003