1. Introduction to Computer Programming
KIC
4/7/2019
Department of Information Technology.
Introduction to Computer Programming
Lec 1
Introduction to Programming
4/7/2019
Introduction to Computer Programming
Introduction to Computer Programming

2. Outlines What is a Computer? Structure of a Computer
Machine Languages, Assembly Languages, and High-level Languages
History of C
Structured Programming
Basics of a Typical C Program Development Environment
Sample Program Explanation

3. What is a Computer?
Device capable of performing computations and making logical decisions
Computers process data under the control of sets of instructions called computer programs
Introduction to Computer Programming
4/7/2019

4. Hardware: Various devices comprising a computer
KIC
Hardware: Various devices comprising a computer
Keyboard, screen, mouse, disks, memory, CD-ROM, and processing units
4/7/2019
Introduction to Computer Programming
4/7/2019
Software : Programs that run on a computer
Introduction to Computer Programming

5. Structure of a Computer
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Structure of a Computer
Introduction to Computer Programming

6. Computer Organization
KIC
Computer Organization
4/7/2019
Storage Unit
Input Units
Output Units
Memory Unit
CPU
Arithmetic and
Logic Unit (ALU)
Control Unit
Introduction to Computer Programming
4/7/2019
Introduction to Computer Programming

7. Computer Organization
Six logical units in every computer:
Input unit Obtains information from input devices (keyboard, mouse)
Output unit Outputs information (to screen, to printer, to control other devices)
Memory unit Rapid access, low capacity, stores input information
Arithmetic and logic unit (ALU) Performs arithmetic calculations and logic decisions
Central processing unit (CPU) Supervises and coordinates the other sections of the computer
Secondary storage unit Cheap, long-term, high-capacity storage, Stores inactive programs

8. Introduction to Computer Programming
4/7/2019

9. What are the Generations of Languages?
4/7/2019
What are the Generations of Languages?
Introduction to Computer Programming

10. Fourth Generation Languages
Fourth Generation Languages
……Add C
Database
High-Level Languages
Machine Language
Assembly Language
Natural Languages
Introduction to Computer Programming
4/7/2019

11. Machine Languages, Assembly Languages, and High-level Languages
Strings of numbers giving machine specific instructions
Example:
Assembly languages
English-like abbreviations representing elementary computer operations (translated via assemblers)
LOAD BASEPAY
ADD OVERPAY
STORE GROSSPAY

12. Machine Languages, Assembly Languages, and High-level Languages
Codes similar to everyday English
Use mathematical notations (translated via compilers)
Example:
grossPay = basePay + overTimePay

13. History of C
Evolved by Ritchie from two previous programming languages, BCPL and B
Used to develop UNIX
Used to write modern operating systems
Hardware independent (portable)
By late 1970's C had evolved to "Traditional C"
Standardization
Many slight variations of C existed, and were incompatible
Committee formed to create a "unambiguous, machine-independent" definition
Standard created in 1989, updated in 1999

14. The C Standard Library
C programs consist of pieces/modules called functions
A programmer can create his own functions
Advantage: the programmer knows exactly how it works
Disadvantage: time consuming
Programmers will often use the C library functions
Use these as building blocks
Avoid re-inventing the wheel
If a premade function exists, generally best to use it rather than write your own
Library functions carefully written, efficient, and portable

15. Structured Programming
Disciplined approach to writing programs
Clear, easy to test and debug and easy to modify
Multitasking
Specifying that many activities run in parallel

16. Basics of a Typical C Program Development Environment
Basics of a Typical C Program Development Environment
Program is created in
the editor and stored
on disk.
Phases of C++ Programs:
Edit
Preprocess
Compile
Link
Load
Execute
Preprocessor program
processes the code.
Loader puts program in memory.
CPU takes each
instruction and executes it, possibly storing new data values as the program executes.
Compiler creates object code and stores it on disk.
Linker links the object
code with the libraries
Loader
Primary Memory
Compiler
Editor
Preprocessor
Linker .
Disk
CPU

17. Compilers (Real-World)
Real life translation
Same to you buddy!
Merry Christmas and Happy New Year!
Huh?

18. Compilers (Computers)
Anybody who has this executable on their computer can then run (use) it.
1) A programmer writes a computer program
3) An executable program is created
2) The compiler translates the program into a form that the computer can understand

19. Introduction to C #include<stdio.h> int main() {
printf(“Hello to C programming”); }

20. Sample Program Explanation
#include<stdio.h>
int main() {
printf(“Hello to C programming”); }
Header File
Main Function
Start
Output Statement
End

21. Preprocessor Directives
In C programming whenever you see lines that begin with a in column 1 are called preprocessor directives (commands)
The #include<stdio.h> directive allows the processor to include basic Input / Output in the program at this point. #

22. stdio.h
This header file is included in all programs where we need to use basic I/O commands e.g.
printf(“”);
Some functions are very difficult and very long to write, these header files contains built in functions to provide us help in writing the programs.

23. Each C program can contain only one main function e.g. int main()
Every C program has a main function, this is where the program starts it’s execution, as this is the first function to execute in the whole c program.
Each C program can contain only one main function e.g.
int main()

24. Function Body
A left brace (curly bracket) -- { -- begins the body of every function. A corresponding right brace -- } -- ends the function body.
int main() { …… }
Main Function
BODY

25. printf(“”); This line is called a C statement
printf(“”); is a function which is used to instruct computer to display something on computer screen
All text, special symbols you will type inside printf(“”); between the double quotations i.e. “……..” will be displayed as it is on your computer screens except few commands like /t, /n, %i etc. e.g.
printf(“Welcome at KIC”);
Notice that the above line ends with a Semicolon ; (every C statement ends with a semicolon i.e. ;)

26. Introduction to Computer Programming
4/7/2019