OOPs : Object Oriented programming pre-requisites. A tutorial on OOPs by an average student.

1.
OOPs
Placement Class 2013
23 September

2.
Pre­requisites
●
OS Stack
●
Variables
●
Functions

3.
The Stack
●
Call­Stack,
Execution­Stack,
Runtime­Stack,
Machine­Stack
●

4.
Variables
●
A variable is an IDENTIFIER for a VALUE

5.
Variables
●
A variable is an IDENTIFIER for a VALUE
●
IDENTIFIERS = (KEY WORDS) U
(QUALIFIED IDENTIFIERS)
●
QUALIFIED ID = (Var Names) U (Class
names) U (Function names) U ...

6.
Variables
●
Question :
●
What is the difference between the
following :
● #define myVar 10
● int myVar = 10;

7.
Variables
QUESTION:
How will this program behave?
Output?

8.
Variables

9.
Variables
Mapping VAR­>Address
VALUE

10.
Variables
Mapping VAR­>Address
VALUE
●
Why not directly VAR­>VALUE mapping?
●
Different data types have different memory reqt
●
int coolness = 5;
Datatype VariableName Value

11.
Variables Memory Reqt
●
INT : 4B
●
FLOAT : 4B
●
DOUBLE : 8B
●
LONG LONG INT : 10B
●
POINTER (int *coolness) = 32b / 64b???

12.
Variables Memory Reqt
●
INT : 4B
●
FLOAT : 4B
●
DOUBLE : 8B
●
LONG LONG INT : 10B
●
POINTER (int *coolness) = 32b / 64b

13.
END OF VARIABLES

14.
Functions
●
Function has the following :
●
Return Type
●
Parameters
●
Function Name (Qualified Identifier)
●
Body

15.
Functions
●
Function has the following in a
Programming language :
●
Return Type
●
Parameters
●
Function Name (Qualified Identifier)
●
Body

16.
Functions
●
Function can be called (evoked) in 2
ways:
●
Call by REFERENCE
●
Call by VALUE

17.
Functions – Call by reference
●
Pass the address of where the value is
stored in memory

18.
Functions – Call by reference
OUTPUT?

19.
Functions – Call by reference

20.
Functions – Call by Value
●
Makes a COPY of the parameters passed
and uses the COPY in the function body

21.
Functions – Call by Value
●
Makes a COPY of the parameters passed
and uses the COPY in the function body
●
This is a form of scoping too

22.
Functions – Call by Value
OUTPUT?

23.
Functions – Call by Value

24.
Functions – Call by Value

25.
Functions – Call by Value
Trivia + Trick Question!

26.
Functions – Call by Value

27.
Functions – TRIVIA
15 years back, before C++ came in,
Address(cool) = Address(coolness)
WHY?

28.
Functions – TRIVIA
15 years back, before C++ came in,
Address(cool) = Address(coolness)
COMPILER OPTIMIZATION!

29.
Next : OOPs