1. LESSON 2 Basic of C++

2. Writing the first program
//my first program in C++ #include<iostream> #include<conio.h> using namespace std; int main() { cout<< “Hello World!”; getch(); return 0; }
Hello World!

3. Structure of C++ Program
hash sign
#include <iostream> #include <conio.h> using namespace std; int main() { }
 Preprocessor directives
 Namespace library
 Main function header
brace
 Open the block
 Write declarations and statements
 Close the block
brace

4. Writing the first program
Source Code
//my first program in C++ #include<iostream> #include<conio.h> using namespace std; int main() { cout<< “Hello World!”; getch(); return 0; }

5. Writing the second program
//my second program in C++ #include<iostream> #include<conio.h> using namespace std; int main() { cout<< “Hello World!”; cout<< “I’m a C++ program”; getch(); return 0; }
Hello World! I’m a C++ program
Hello World!

6. Comments
Text that are inserted into the source code to explain what the code is doing.
Two types of comments:
Line comment //
Block comment /* */

7. Comments Example –1 #include<iostream> using namespace std;
int main() {
cout <<"I play Football";
// Abdullah
// ID=3333
return 0; }
Example -2
/* Abdullah
ID =3333 */

8. Program with Comment
//my first program in C++ #include<iostream> #include<conio.h> using namespace std; int main() { cout<< “Multi-line comment”; /*This line is part of the block or multi-line comment. This line is also part of the block comment */ cout<< “Line comment 1”; //This line comment takes up an entire line. cout<< “Line comment 2”; getch(); return 0; }
Multi-line comment Line Comment1 Line comment2
Multi-line comment
Multi-line comment Line Comment1

9. endl Command
#include<iostream> #include<conio.h> using namespace std; int main() { cout<< “Hello”; cout<< “How are you.”; cout<< “What is your name?”; getch(); return 0; }
Hello How are you. What is your name?
Hello
Hello How are you.

10. endl Command
#include<iostream> #include<conio.h> using namespace std; int main() { cout<< “Hello” << endl; cout<< “How are you.” << endl; cout<< “What is your name?” << endl; getch(); return 0; }
Hello
How are you.
What is your name?
Hello
Hello
How are you.

11. Variables
Simply a name chosen by the programmer that is used to refer computer storage location.

12. Variables
Variables may consist of letters, digits and underscore ( _ ) character with the following condition:
They must begin either with a letter or an underscore.
Uppercase and lowercase are significant
Space is not allowed
Keywords are not allowed as variable names

13. List of C++ Keywords

14. Valid/Invalid Variable Names
John
int
Name
const
char
NAME
s_name
first_name
_name
first-name
1man
first name
@name
v.a.l.u.e

15. Data Types Specific category of information that a variable contains.
Type Category
Description
Keyword
Integer
Positive or negative number with no decimal
int
Floating Point
Numbers containing decimal places
float
double
long double
Character
Text
char
Boolean
True(1) or False(0)
bool

16. Declaration Statement
Naming a variable and specifying the data type.
int
float
double
long double
char
bool
type name;
user defined name based on the naming RULES.

17. Declaration Statement - Example
int sum; char gender; double studentgpa;
int a,b,c;
int a;
int b;
int c;
int num = 15;
float grade1=81.0;

18. Literals int float char string bool -259 -13 200 -6.16 -4.4 2.7541
200
float
-6.16
-4.4
2.7541
10.5
char
‘z’
‘p’
‘x’
‘a’
string
“Hello World”
“How do you do?”
“Ali”
“Diploma 1”
bool
true
false

19. Operating with variables
#include <iostream>
#include <conio.h>
using namespace std;
int main() {
int a,b;
int result;
a=5;
b=2;
a=a+1;
result = a–b;
cout <<“Result equals to”<<result;
getch();
return 0; } a 6 a 5 a 2 b b
result 4
result
Result equals to 4

20. Constants Literal Symbolic Memory Expression with a fixed value.
Ways to use constants:
Literal
Symbolic
Memory
float pi=3.1416;
#define pi ;
const double pi=3.1416;

21. Operating with const #include <iostream> raduis=20;
#include <conio.h>
using namespace std;
int main() {
const float PI=3.1416;
float radius=5;
float area;
area=radius*radius*PI;
cout<<“The area is”<<area
<<“with a radius of 5.\n”;
raduis=20;
area=radius*radius*PI;
cout <<“The area is ”<<area
<<“with a radius of 20.\n”;
getch();
return 0; }
The area is with the radius of 5.
The area is with the radius of 20.
The area is with the radius of 5.

22. Operating with const #include <iostream> raduis=20;
#include <conio.h>
#define PI ;
using namespace std;
int main() {
float radius=5;
float area;
area=radius*radius*PI;
cout<<“The area is”<<area
<<“with a radius of 5.\n”;
raduis=20;
area=radius*radius*PI;
cout <<“The area is ”<<area
<<“with a radius of 20.\n”;
getch();
return 0; }
The area is with the radius of 5.
The area is with the radius of 20.
The area is with the radius of 5.

23. cout
is output command that sends data given to it to the standard output device.

24. Operating with cout #include <iostream> #include <conio.h>
using namespace std;
int main() {
int a,b;
float x,y;
a=10;
b=20;
x= ;
y = ;
cout <<“a=”<<a
<<“, b=”<<b
<<“, x=”<<x
<<“, y=”<<y;
getch();
return 0; } 10 a a 20 b b x x y y
A=10, b=20, x= , y=

25. cin Command reads in information from the keyboard. int age;
cin >> age;
float salary;
cin >> salary;

26. Operating with cin #include <iostream> #include <conio.h>
using namespace std;
int main() {
int number;
cout<<“Enter number: ”
cin>> number;
cout>>”You entered ” number;
getch();
return 0; } 27
number
number
Enter number: 27
You have entered 27
Enter number:
Enter number: 27

27. Backup Slides

28. Comments Line comment Sample 1 Sample 2
cout << “Hello world!” <<endl; //Everything from here to the right is ignored
Sample 2
cout << “Hello world!” <<endl; //cout and endl live in the iostream library
cout << “It is nice to meet you” <<endl; //this code is hard to read
cout << “Yeah!” <<endl; //specially when lines are different length

29. Comments Sample 3 //cout and endl live in the iostream library
cout << “Hello world!” <<endl;
//this code is easir to read
cout << “It is nice to meet you” <<endl;
//don’t you think so?
cout << “Yeah!” <<endl;

30. Comments Multi-line Comment Sample 1 Sample 2
/* This is a multi-line comment
This line will be ignored.
so will this one. */
Sample 2
/* This is a multi-line comment.
* the matching asterisks to the left
* can make this easier to read */