1. Programming Languages

2. Introduction
The computer programming involves designing the computer programs to solve different kinds of problems as well as to control different operations of the computer
A computer is nothing without a computer program
A computer program is designed after understanding the problem
To develop a correct program, the programmer must write program instructions in the proper sequence

3. Example To find out the average marks of the student
Get the marks of all subjects of the student
Calculate the total marks
Calculate the average marks
Print the average marks

4. Algorithm
The step-by-step procedure for the solution of the problem is called algorithm
The algorithm represent the sequence of steps or instructions and the order in which these steps are taken for the solution of the problem
An algorithm provides the procedure for the solution of the problem in general terms only
An algorithm is written before writing the actual computer program
It is written by using short English statements

5. Example Program to find average and sum of three numbers
INPUT “Enter the first number: ” ; X
INPUT “Enter the second number: ” ; Y
INPUT “Enter the third number: ” ; Z
LET SUM = X + Y + Z
AVG = SUM/3
PRINT “Sum of three numbers is: ” ; SUM
PRINT “Average of three numbers is: ” ; AVG
END

6. Altering Order of Algorithm
Algorithm operations are ordered in that there is first instruction, a second instruction etc
An algorithm must have the ability to alter the order of its instructions
An instruction that alters the order of an algorithm is called a control structure

7. Types of Control Structures
Sequential Structure
Conditional Structure
Iterative Structure

8. Example

9. Pseudo code Pseudo code is a problem solving tool
It is a generic way of describing an algorithm without use of any specific programming language syntax
Statements in pseudo code represent the logic of actual computer program in natural language
Cannot be compiled nor executed
Also called program design language

10. Example If student’s marks is greater than or equal to 50% Else
Print “Passed”
Else
Print “Failed”

11. Flow Chart
Graphical or symbolic representation of the solution of a problem
Graphical representation of algorithm or pseudo code
Used to describe the solution of the problem
Easy to understand
Plan to be followed for coding a program
Errors in the logic of the program can be detected very easily in flowchart

12. Symbols of Flow Chart
Each step in solving the problem is represented by a different symbol
Each symbol also contains a short description about the step
The flow chart symbols are linked together with arrows that show the direction of flow of data or control

13. Operating System Functions

14. Example

15. Example

16. Example

17. Programming Languages
A language is defined as a way of communication between two persons
Programming language is a means of communication between computer and the user
A computer program is written or prepared in programming language
Each programming language has a set of alphabets and rules for writing computer programs

18. Types of Programming Languages
Low Level Language
Machine Language
Assembly Language
High Level Language
FORTRAN
COBOL
C++

19. Types of High Level Language
Procedural language
Non-Procedural language
Object Oriented Programming languages

20. Advantages of High Level Languages
Easy to learn
Easy to understand
Easy to write program
Easy to detect and remove errors
Built in library functions
Machine independence

21. Difference between Low Level & High Level Languages
Low Level Languages is close to machine language, while High level languages is close to human language
Low Level Languages is machine dependent, while High level languages is machine independent

22. Programming Techniques
Structured Programming
Object Oriented Programming
Event Driven Programming
Visual Programming

23. Language Processors
A computer understands instructions in machine code
A program written in any high level programming language is called the source program
The source code cannot be executed directly by the computer
The source program must be converted into machine code before running it on the computer
“The special translator system software that is used to translate the program written in high level language(or assembly language) into machine code is called language translator or language processor”

24. Types of Language Processors
Compiler
Interpreter
Assembler

25. Difference between Compiler & Interpreter
Compiler translates the source code into object code as a whole, while interpreter translates the source code into machine code statement by statement
Compiler creates an object file while interpreter does not create object file

26. References
Introduction to Information Technology by Riaz Shahid, CM Aslam and Safia Iftikhar
The Concepts of Information Technology by Imran Saeed, Ahsan Raza, Tariq Mehmood and Zafar Hussain