1. Introduction to Programming Using C Introduction to Computer Programming

2. 2 Contents Computers Programming

3. 3 What is a Computer ? We live in a world of electronic devices Not all of these are computers What makes a computer different from the other devices?

4. 4 What is a Computer ? A computer can – Receive data from the outside world – Process this data in some way to compute results – Store data for varying periods of time – Output results to the outside world – Allow the user to have the computer remember a series of operations to perform so that the same thing can be done again

5. 5 How does this differ from a calculator? A calculator can – Accept input from the world via the keys – Perform calculations by pressing keys – Store values in its memory – Output results A calculator cannot – Store a series of operations to be performed later

6. 6 Programmability The ability to store a series of operations and perform them later is called programmability It is programmability which distinguishes a computer from a calculator Programmability allows – Long sequences of operations to be stored – These sequences to be repeated any time – Conditional logic to be included

7. 7 Conditional Logic Conditional logic allows a computer to – Compare two values – Do different things depending on the result of the comparison For example – If customer age >= 65 Apply senior discount – Otherwise Charge regular price

8. 8 Hardware & Software Hardware is – The physical parts of the computer The keyboard and display The chips which make it work Software is – The series of programs which are stored and instruct the hardware to do what we want – This course is an introduction to how to write software Firmware – Software permanently stored in the computer

9. 9 What is Programming ? Programming is the act of writing a computer program This program will tell the hardware of the computer what operations need to be performed These programs are written in one of several programming languages

10. 10 Programming Languages Much more precise than human languages Much smaller than human languages Many are based on a mathematical notation Take much less time to learn than a human language

11. 11 Programming Computers are dumb They are glorified calculators Therefore – They do exactly what they are told to do – You must be very careful that you tell them to do the right thing – This requires attention to detail

12. 12 Programmers Many people do not have the patience to program computers Many people do not like to deal with the low- level details of programming computers People who like math often like programming However, there is another group who never liked math but like programming

13. 13 The Programmer Personality Patient Persistent Precise Likes to figure out how to solve small problems Can plan what is needed to solve a larger problem Confidence that they can solve to problem

14. 14 How much math do you need? You need high school math You need to be good at basic math For some areas, like game programming, you will need more math In general business programming, you need relatively little math

15. 15 Computer Architecture Before looking at programming, it helps to understand how a computer works A computer consists of – A Central Processing Unit (CPU) – Memory for storing short-term data – Disk drives for long-term storage – Keyboards for data input – Displays and printers for output

16. 16 Computer ArchitectureProcessor Control Unit Arithmetic Logic Unit (ALU) Input Devices Storage Devices Output Devices  CPU Interprets and carries out basic instructions that operate a computer Memory DataInformation Instructions Data Information Control Unit  Control unit directs and coordinates operations in computer  Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations  Also called the processor

17. 17 Data Representation Recognize only two discrete states: on or off Use a binary system to recognize two states Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)

18. 18 Memory  Electronic components that store instructions, data, and results  Consists of one or more chips on motherboard or other circuit board  Each byte stored in unique location called an address, similar to seats in a concert hall

19. 19 Storage Devices Magnetic disk drive Floppy disk drive CD / DVD Drive Tape DriveFlash Drive

20. 20 Input / Output Devices Monitors Keyboards Mice Printers

21. 21 The Programming Process 1. Gather the requirements 1. You have to know what the program need to do 2. Analyze the requirements 1. Read and understand what is needed 3. Design a solution 1. Plan what the program will look like 4. Write the program 5. Compile the program 6. Test the program

22. 22 Compilation Computers do not speak C Each computer has its own language in the same way that each calculator works slightly differently A compiler is a program which translates C to the native language of the computer You must compile the program before it can be executed

23. 23 Writing the program Writing the program is usually done with a text editor Do not use a word processor Once the program is written, it is then compiled

24. 24 Testing the Program Just because you write a program does not mean it is correct It must be tested This executes the program with a variety of data and then checks the results Locating te source of a problem is called debugging The program is modified to fix the bug, recompiled, and tested again

25. 25 The C Programming Language One of many programming languages Written at AT&T in the 1970s Used to write the UNIX operating system Has become one of the most popular programming languages Based on the concept of structured programming

26. 26 Problems with C It is a low-level language Gives the user the ability to make mistakes which are really hard to find Is not object-oriented – Although it leads you into the next course where you will learn C++, the object-oriented version of C – C is a subset of C++ and you must know C to study C++