The document provides an overview of C++ programming, detailing comments, variable declaration, data types, and basic arithmetic operations. It explains the syntax rules, such as the necessity of semicolons and the case sensitivity of identifiers. The document includes examples of input/output operations and the usage of arithmetic operators, which are essential for coding in C++.

1. Comments have two forms in C++
//I am a Single line comment
/*I am a Multi-line
comment and
I can span
multiple lines
This is my line number 5
*/

2. #include <iostream.h>
int main( )
{
cout <<"Welcome to CS102";
return 0; //this is a simple program
}//end block of main

3. int main(){cout <<"Welcome to
CS305";return 0;}
Bad programming style!

4. Statements end with a semi-colon ;

5.  Omitting a semicolon is a syntax
error.
 Other errors could be:
•mis-typing a keyword
•omitting braces or parenthesis
•forgetting << operator in cout
•…
 Compiler can catch such errors.

6. More cout examples

7. Constants
cout<< -23;
cout<< “Hello”;
cout<< 24.5;

8. Constants
cout<< -23 <<“n”;
cout<< “Hello”<<“n”;
cout<< 24.5 <<“n”;

9. Programs need to manipulate
data.

10. Programs need to manipulate
data.
C++ uses variables to name and
store data.

11. Variables and Identifiers
The compiler assigns a memory location to
each variable in the program.
The name of the variable (the identifier) is
used to refer to that memory location.

12. Variables and Identifiers
 Identifiers

case sensitive

must begin with a letter or underscore

consist of letter, digits and underscore only (no
special characters)

can not use reserve words (key words)
Use meaningful names for variables.

13. Variable declarations
What kind of data would you be
storing in a variable.

14. Variables – must be declared before use.
int value;
value = 23;
cout<< value;

15. Variables – must be declared before use.
int value;
value = 23;
cout<< value;
Assignment statement

16. Simple I/O
cin

Used for input

uses the >> (input operator)
cout

Used for output

uses the << (output) operator

17. /*****************************************************
* Sum two numbers
******************************************************/
#include <iostream.h>//declares standard I/O library
int main()//must have one and only one function named main
{
int number1, number2; //declare two integer variables
cout << “enter two integers” << endl;//prompt for input
cin >> number1 >> number2; //input values from keyboard
cout << number1 + number2; //output sum to the screen
return 0;
}//end block of main

18. #include <iostream.h>
int main()
{
int number_of_pods, peas_per_pod, total_peas;
cout<<"Press return after entering numbern";
cout<<"Enter number of podsn";
cin>>number_of_pods;
cout<<"Enter number of peas in a podn";
cin>>peas_per_pod;
total_peas = number_of_pods * peas_per_pod;
cout<<"If you have ";
cout<<number_of_pods;
cout<< " pea podsn";
cout<<"and ";
cout<<peas_per_pod;
cout<<" peas in each pod, thenn";
cout<<"you have ";
cout<<total_peas;
cout<<" peas in all the pods.n";
return 0;
}

19. #include <iostream.h>
int main()
{
int number_of_pods, peas_per_pod, total_peas;
cout<<"Press return after entering numbern";
cout<<"Enter number of podsn";
cin>>number_of_pods;
cout<<"Enter number of peas in a podn";
cin>>peas_per_pod;
total_peas = number_of_pods * peas_per_pod;

20. cout<<"If you have ";
cout<<number_of_pods;
cout<< " pea podsn";
cout<<"and ";
cout<<peas_per_pod;
cout<<" peas in each pod, thenn";
cout<<"you have ";
cout<<total_peas;
cout<<" peas in all the pods.n";
return 0;
}

21. Enter number of pods
20
Enter number of peas in a pod
8
If you have 20 pea pods
and 8 peas in each pod, then
you have 160 peas in all the pods.

22. C++ Data Types

char

short

int

float

double

…
--

23. Type specifiers e.g. int, long, short etc
Specific ranges of values are system dependent
 On many systems short integer ranges from -32768 to
32767
 unsigned short has range of values 0 to 65535
 int 4 bytes -2147,438,648 to 2,147,483,647
 float 4 bytes 3.4E-38 to 3.4E+38
 Double 8 bytes 1.7E-308 to 1.7E+308

24. Declarations and Initialization
double dx ;
dx=3.5 ;
OR
double dx=3.5 ;

25. Declarations and Initialization
//(comma separated)
double a, b, c=5.6, d ;
double r1,
r2,
r3; //(white spaces ignored)
/*All declarations and
statements must end with
semicolon ; */

26. int big=980000;
short small;
cout<<"big="<<big<<endl;
small=big; //don't do this
cout<<"small="<<small<<endl;

27. int big=980000;
short small;
cout<<"big="<<big<<endl;
small=big; //don't do this
cout<<"small="<<small<<endl;
big=980000
small=-3040

28. short small = 980000;
cout << small << endl;
-3040

29. Character Data

Each character corresponds to a binary code

Most commonly use binary codes are ASCII
(American Standard Code for Information
Interchange)
Character ASCII Code Integer Equivalent
% 0100101 37
3 0110011 51
A 1000001 65
a 1100001 97
b 1100010 98
c 1100011 99

30. Arithmetic Operators
 Addition +
 Subtraction -
 Multiplication *
 Division /
 Modulus %

31. Arithmetic Operators
 Addition +
 Subtraction -
 Multiplication *
 Division /
 Modulus %

Modulus returns remainder of division between two
integers

% cannot be used on float or double

32. 
Example
5 % 2 evaluates to ?
10 % 2 evaluates to ?

33. 
Example
5 % 2 evaluates to 1
10 % 2 evaluates to 0

34. Arithmetic Operators
Division between two integers results in an
integer.
The result is truncated, not rounded

35. Modulo operation
17 / 5 evaluates to
17 % 5 evaluates to

36. Modulo operation
17 / 5 evaluates to 3.
17 % 5 evaluates to 2.

37. Example:
5/3 evaluates to ?
3/6 evaluates to ?

38. Example:
5/3 evaluates to 1
3/6 evaluates to 0

39. Priority of Operators
1 Parentheses Inner most first
2 Unary operators Right to left
(+ -)
3 Binary operatorsLeft to right
(* / %)
4 Binary operatorsLeft to right
(+ -)

40. Precedence
Order of mathematical operations is important.
Examples:
(3+2)*4 = 5*4 = 20
3+(2*4) = 3 + 8 = 11
· * and / evaluated before + and -
Example: 3+2*4 evaluated as 3+(2*4)

41. Precedence
· If precedence is equal, then evaluate from left to
right.
Examples:
3+2+5 = 5 + 5 = 10
3*2/5 = 6/5 = 1
· Parentheses enforce evaluation order
Example: (3+2)*4 = 5*4 = 20

42. Unary operators: +, -
Unary operators: +, -
-3, +17 allowed
Example: 4*(-3) = -12

43. Assignment Operators
= assignment operator
Compound Assignment Operators
operator example equivalent statement
+= x+=2; x=x+2;
-= x-=2; x=x-2;
*= x*=y; x=x*y;
/= x/=y; x=x/y;

44. Example
x = 4;
x *= 5;

45. Example
x = 4;
x *= 5; // x = 20

46. Arithmetic Operators
unary operators
• auto increment ++
–post increment x++;
–pre increment ++x;
• auto decrement - -
–post decrement x- -;
–pre decrement - -x;

47. x++ is executed after it is used
x = 7;
y = x++;
++x is also equivalent to x = x+1
++x executed before it is used
x = 7;
y = ++x;
--x is equivalent to x = x-1
-- works just like ++, but with subtraction
instead of addition

48. x++ is executed after it is used
x = 7;
y = x++; // x = 8, y = 7
++x is also equivalent to x = x+1
++x executed before it is used
x = 7;
y = ++x; // x = 8, y = 8
--x is equivalent to x = x-1
-- works just like ++, but with subtraction instead of
addition

49. Shortcuts
· n++
equivalent to n = n + 1
read as "add 1 to n"
· n--
equivalent to n = n - 1
read as "subtract 1 from n"
· s += n
equivalent to s = s + n
read as "add n to s"
· s -= n
equivalent to s = s - n
read as "subtract n from s