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CAVITE STATE UNIVERSITY
T3 CAMPUS
Department of Information Technology DCIT 25 – Data Structures and Algorithms

Week 5: The Point of Pointers
Objectives: After the completion of the chapter, students will be able to:
 Learn the concept of Pointers
 Assign an Address to a Pointer
 Perform Pointer to Pointers

Pointers
Whenever you reference the name of a variable, the name of an element of a structure,
or the name of an attribute of a class, you are telling the computer that you want to do
something with the contents stored at the corresponding memory location.
In the first statement in the following example, the computer is told to store the letter A
into the memory location represented by the variable grade. The last statement tells the
computer to copy the contents of the memory location represented by the grade variable and
store in in the memory location represented by the oldGrade variable.
char grade = ‘A’
char oldGrade;
oldGrade = grade;

A pointer is a variable and can be used as an element of a structure and as an attribute
of a class in some programming languages such as C++, but not Java. However, the contents
of a pointer is a memory address of another location of memory, which is usually the memory
address of another variable, element of a structure, or attribute of a class.

Declaring a Pointer
A pointer is declared similar to how you declare a variable but with a slight twist. The
following example declares a pointer called ptGrade. There are four parts of this declaration.
 Data Type – The data type of the memory address stored in the pointer.
 Asterisk (*) – Tells the computer that you are declaring a pointer.
 Variable Name – The name that uniquely identifies the pointer and is used to reference
the pointer within your program.
 Semicolon – Tells the computer this is an instruction (statement)
char *pgrade;

Data Types and Pointers
As you will recall, a data type tells the computer the amount of memory to reserve and
the kind of data that will be stored at the memory location. However, the data type of a pointer
tells the computer something different. It tells the computer the data type of the value at the
memory location whose address is contained in the pointer.
The Asterisk (*) used when declaring a pointer tells the computer the amount of
memory to reserve and the kind of data that will be stored at that location. That is, the memory
size is sufficient to hold a memory address, and the kind of data stored there is a memory
address.
The following example declares four variables. The first statement declares an integer
variable called studentNumber. The second statement declares a char variable called
grade. The last two statements each declare a pointer. The figure depicts memory reserve by
these statements. Assume that a memory address is 4 bytes for this example:

int studentNumber
char grade;
char *ptGrade;

int *ptStudentNumber;
The char data type in the ptGrade pointer declaration tells the computer that the
address that will be stored in ptGrade is the address of a character. The contents of the
memory location associated with ptGrade will contain the address of the grade variable.

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