Computer programming lecture – 41 to 42

Lecture – 41 to 42Computer Programming

14 Computer Systems Engineering – Second Semester

By: Mr. Ali Asghar Manjotho, Lecturer, CSE-MUET

Contents

• Structure (LL 02)

• Defining Structure in C++ (LL 04)

• Defining Car Structure in C++ (LL 04)

• Defining Point Structure in C++ (LL 04)

• Defining Time Structure in C++ (LL 04)

• Declaring Structure Variables in C++ (LL 04)

• Initializing Structure Variables in C++ (LL 04)

• Accessing Structure Members in C++ (LL 04)

• Structure of Structure in C++ (LL 04)

• Rectangle Structure in C++ (LL 04)

• Program Examples (LL 04)LL 02 = Learning Level 02 – Comprehension, LL 04 = Learning Level 04 – Analysis

Ali Asghar Manjotho, Lecturer CSE-MUET 2

Structure

• Single variable can store only one value at a time.

• Single array can store multiple values at a time but they all must be of same data type.

• What if you want to store the data which is collection of different data types.

• In this case neither variable nor array is helpful.

• Here comes the role of a structure.


Structure

• Structure is the collection of heterogeneous data items unlike an array.

• Structure can also be defined as a collection of a fixed number of components in which the components are accessed by name. The components may be of different types.

• All the data items in a structure may or may not be of same data type.

• There are some data items which are group of multiple values instead of a single value.


Structure

Q: In what data type of a variable you will store a time?

A: As the time is not a single valued item. It has three integer values i.e. Hours, Minutes and Seconds. Hence we create a structure of three integer variables to store time.

Time{

int hours;int minutes;int seconds;

}


Structure

Q: In what data type of a variable you will store a point?

A: As the point is not a single valued item. It has two integer values i.e. X, and Y. Hence we create a structure of two integer variables to store a point.

Point

{

int x;

int y;

}


Structure

Q: We want to store the data about a car, the data contains the information about the name, color, company, max speed and transition mode of the car. In what data type of a variable you will store all the information of car?

A: As the car data is not a single valued item. It has five values i.e. Name, Company, Color, Maximum Speed and Transition mode (Automatic = 0 or Manual = 1). Hence we create a structure of five variables to store car.

Car{

string name;string company;string color;float speed;bool transition;

}


Defining Structure in C++

• In C++ the structure is defined by the keyword struct followed by the name of the structure.

• Then we specify all the variables of different data types, which constitute to form a structure.

• All the variables inside the structure are called as structure members.

• Finally the definition is terminated by the semicolon.

• Consider the Car structure:


Defining Car Structure in C++


struct Car

{

string name;

string company;

string color;

float maxspeed;

bool transition;

};

Structure Name

Structure Members

Defining Point Structure in C++


struct Point

{

int x;

int y;

};

Defining Time Structure in C++


struct Time

{

int hours;

int minutes;

int seconds;

};

Declaring Structure Variables in C++

• Once you have created a structure, it can be treated as new data type.

• You can create the variables of the structure in the same way as you create the variables for built-in data types like; int, float, char etc.

• A structure variable can be declared by just writing the name of the structure followed by the variable name.


Declaring Structure Variables in C++


Car mycar ;

Point p1 ;

Time now ;

Variable Name

Structure Name

Initializing Structure Variables in C++

• While initializing the structure variable we will also provide the values of each of the member of the structure.

• All the members values are placed in curly brackets { } , each value separated by comma ( , ).

• The order of the values does matter.


Initializing Structure Variables in C++


Car mycar = {"Corolla", "Honda", "Maroon", 350.5, 0};

Point p1 = {5,3};

Time now = {8,35,14};

Accessing Structure Members in C++

• Once structure is defined and its variable is created, we can access the individual members of the structure with the help of dot operator ( . ).

• The dot operator is also called as member access operator.


Accessing Structure Members in C++


Point p1;

p1.x = 10;

p1.y = 14;

cout<<"X = "<< p1.x <<endl;

cout<<"Y = "<< p1.y <<endl;

p1.xMember Access Operator

Structure Variable Member

Structure of Structure in C++

• If one of the member of a structure is itself a structure then the parent structure is called as the structure of structure.

• It is also termed as nested structure.

• You can nest as many structures as required i.e. there is no any limitation on the levels of nested structures.


Rectangle Structure in C++

• Consider the example of Rectangle structure.

• A rectangle can be defined as:

• Combination of left-top and right-bottom corner points.

• Combination of left-top corner point, width and height.




struct Point

{

int x;

int y;

};

struct Rectangle

{

Point left_top;

Point right_bottom;

};

Rectangle rect = {{0,0},{10,12}};



struct Point

{

int x;

int y;

};

struct Rectangle

{

Point left_top;

float width;

float height;

};

Rectangle rect = {{0,0},12.5,14.8};

Program ExamplesStructures in C++


Program Example 01

Problem Statement:

Write a program in C++ that creates structure TIME. Initialize two variables to store the starting and ending time of the race. The program should calculate the elapsed time in the third TIME variable and display it.


Program Example 01


Program Example 01


Program Example 02

Problem Statement:

Write a program in C++ that creates a Rectangle structure. Initialize two rectangles and find the third rectangle that encloses both the rectangles.


x

y

(0,0)

Program Example 02


Program Example 02


Program Example 02


Program Example 03

Problem Statement:

Write a program in C++ that creates structure STUDENT. The STUDENT structure contains the following members: Name, Roll number, Attendance Marks, Test1 marks, Test2 marks and Test3 marks. Initialize two variables to store the record of two students. The program should display the name, roll number and total sessional marks of both the students.


Program Example 03


Program Example 03


Program Example 03


Education

Computer programming lecture – 41 to 42