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Object Oriented
Programming using C++
Lecture – 3
Structures
Why Structures
Data types, e.g., float, int, char, etc., are used to
store single piece of information or value in a variable
However; in reality we need the data to be organized
in sets or a piece of collection
E.g. I am recognized by: First Name Last Name NIC / driving license Number My height etc. All this information represents an entity, i.e., me, and it needs to be recorded as a set
First Name Last Name NIC Number Height
Structure design
Different data-types are used to identify individual
item
String or char[] for first name String or char[] for last name int can be used for NIC ?? Or you can make a sub-structure with three fields to identify each section of your NIC int for height
Its all about how you design it!
First Name Last Name NIC Number Height
This group or record is called a
structure , and individual fields
are its members
Usman Younis
Structure
E.g.,
struct NIC { int field1; int field2; int field3; };
struct Record { char first_name[10]; char last_name[10]; NIC Identification_number; int height; };
First Name
NIC Number
NIC
Char[]
Last Name
Height
Char[] NIC int
Char[] Char[] int
Person 1 Person 2
Structure Assignment
Structures can be used as variables, such that the
value is assigned to another variable of the same
type.
E.g.
Record Person1 = {“usman”, “younis”, {123, 123, 1}, 123};
Record Person2;
Person2 = Person1;
usman younis 123, 123, 1 123
usman younis 123, 123, 1 123
Person1 Person
Structure Assignment (contd..)
However; you cannot perform arithmetic,
comparison, etc., operations on these variables
Person1 + Person
If(Person1 < Person2)
You have to use “.” (DOT) operator to access the
members. No direct access
cout<<Person1;
Structures as an Array
We can create a list of records using structure
arrays
Record Family[6]; //a family of 6 persons
Like an ordinary array, the data will be stored
sequentially
int
[0]
int
[1]
int
[2]
int
[3]
int
[4]
[0] [1] [2] [3] [4]
An array of
Integers
An array of
Structures
Structures as an Array (contd..)
The members are accessed the similar way, i.e.,
using the “.” (DOT) operator
E.g.
for( int i = 0; i < 6; i++)
cout<<Family[i].first_name;
