Page 240 - DCAP404 _Object Oriented Programming

Unit 11: Pointers and Dynamic Memory Management

pointer, de-references the pointer’s value. When you see * operator used, think of the phrase Notes
“value pointed to”.

!

Caution The * operator retrieves the value that is “pointer to” by variable it proceeds.

Self Assessment

Fill in the blanks:
1. A pointer is a variable that is used to store a …………………….. address.
2. There are two important pointer operators such as ‘*’ and ……………….. .

3. The ‘*’ operator is called the ……………………. operator.
4. Every variable is located under unique location within a computer’s memory and this
unique location has its own …………………… address, the memory address.

11.2 Declaring Pointers

A pointer is a special variable that return the address of a memory. If you need to declare a
variable to hold your age, you might use the following variable declaration:
int age = 18 // declares to variable to hold my age

Declaring age this way does several things. Because C++ knows that you need a variable called
age, C++ reserves storage for that variable. C++ also knows that you will store only integers in
age, not floating-point or double floating point data. You also have requested that C++ store the
value of 18 in age after reserving storage for that variable.
Suppose that you want to declare a pointer variable, not to hold your age but to point to age, the
variable that hold your age. p_age might be a good name for this pointer variable. Figure given
below shows an illustration of what you want to do. This example assumes that C++ store age at
address 1002, although your C++ compiler arbitrarily determines the address of age, and it
could be anything.

Figure 11.1: Page Contains the Address of Age; p_age to the Age Variable

Address Memory

Age at 350,606 30 p_age “points to age”
.
.
.
p_age at 356, 982 350606

Top of memory

To declare the p_age pointer variable. You should do the following:
int*_age; // declare an integer pointer
As with the declaration for age, this line reserves a variable called p_age. It is not a normal
integer variable, however, because of the C++ knows that this variable is to be a pointer variable.

LOVELY PROFESSIONAL UNIVERSITY 233