1. Introduction to C Programming
ET2560 Introduction to C Programming
Introduction to C Programming
Unit 1
Unit 1 Presentations

2. What is a Program?
Unit 1: Programs

3. Recall: A Computer System is …
Hardware
Central processing unit (CPU)
Main memory (RAM, ROM)
Secondary memory (Hard disk, CD, DVD, flash drive, etc)
Input devices
Output devices
Network interface
Power supply
Software
Firmware
Operating system
Application programs

4. What is a Software “Program”?
A set of instructions
Performs a specific task
Required to make the hardware “do something”
The hardware “runs” or “executes” it
Must be in main memory (RAM or ROM)
Is written in machine language (specific to a CPU)
Consists of binary ‘1’s and ‘0’s

5. How a Program gets into Memory
It is always stored in memory (ROM)
Firmware such as a PC BIOS
Embedded systems contain ROM or Flash
From secondary storage when needed
Read from the Hard Disk into main memory
Read directly from a CD or DVD into main memory
Via the network
Automatic updates from the program vendor
Web pages and web applications with active content
Mobile applications
Cloud computing

6. Programs are Very Diverse …
Mobile applications – Info services and transactions
Web applications – Web pages, shopping, Virtual Library
Business applications – Word processing, , accounting
Leisure applications – Games, e-book readers
Educational applications – Language learning, encyclopedia
Batch data processing – Payrolls, bank statements
Server software – Provide information services via web
Operating systems – Control hardware, software, security
Control systems – Automation, energy management
Embedded software – Routers, printers, appliances, automobiles, cameras, watches, cell phones, lighting control

7. …But Programs Have Much in Common
Programs process information
Information is stored in the form of binary data
Different types of information use different data types
Programs acquire input data
Programs produce output data
Programs are implementations of algorithms
Algorithms are precise solutions to problems
Programs are written in programming languages
May be compiled (translated) to machine language
May be compiled to intermediate form and then interpreted

8. This Class Introduces Programming
Programming is the discipline and art of creating software
Focus is on fundamental concepts and building skills
Examples, labs, and projects will use the C language
Prerequisite class – NT1110 Computer Structure & Logic
Future classes:
ELCT: ET2640 Microprocessors and Microcontrollers
ELCT: ET2750 Programmable Logic Controllers
EECT: ET4560 C++ Programming
EECT: ET4640 Embedded Systems

9. Programs Relevant to Electronics
Unit 1: Programs

10. Program-based Solutions
Programs used to solve electrical engineering problems
Solutions of equations needed for design and analysis
Example: Iterative calculations of roots of complex polynomials
Example: – Knowledge computation engine
Try: “0.45 ohms per foot for 100 meters”
Simulation software to try circuit design before building
Multisim
Chip design software
Cost is hundreds of thousands of dollars per workstation
One design engineer can access immense libraries of knowledge
Simulations can save millions in time and manufacturing costs

11. What is a Control System?
An electronic control system is a device that:
Regulates a process (such as a manufacturing system)
Components:
Sensors – Convert physical variables to electronic signals
Controllers – Based on sensor data, send signals to actuators
Actuators – Use electronic signals to affect physical world
Example: A commercial baking oven
Example: An automobile engine
The controller can be …
Analog electronics
Hard-wired digital electronics
A programmable computer-based controller

12. Benefits of Programmable Control
Flexibility – can be reprogrammed
Upgradable
Can have optional features
Defects can be easily repaired
Lower engineering costs
Standard hardware designs available
Software designs can be reused
Self-testing and error reporting
Programmable logic controllers – PLCs
Off-the-shelf hardware
Simplified programming

13. Embedded Systems Found everywhere as part of electronic devices
Examples: Watches, calculators, appliances, irrigation and lighting systems, copiers, traffic lights, MP3 players
Pre-programmed computer
Dedicated to a few functions inside a device
Often must be real-time (respond “immediately” to events)
Non-stop computing (continuously functioning)
Traditionally viewed as non-reprogrammable
Reprogrammability is becoming commonplace
Therefore, programming is essential to electronics students!

14. How are Programs Created?
Unit 1: Software Development Process

15. Creating a Program Use problem solving skills Create an algorithm
Implement the algorithm in a programming language
Understand the programming model
Use specialized tools
Use software engineering methodology

16. Use Problem-Solving Process
Heuristics (strategies) for successful problem solving
Five-step process (from Strategies for Creative Problem Solving, Fogler et al)
Define the problem
Generate possible solutions
Evaluate and decide on a solution
Implement the solution
Evaluate the solution

17. Develop Problem-Solving Skills
A good programmer is an effective problem solver
Has a belief that problems can be solved through analysis
Develops a high level of problem-solving skills:
Active – Makes sketches, draws figures, asks questions
Methodical – Keeps track of progress in solving the problem
Detail-oriented
Takes great care to understand facts and relationships
Checks and re-checks for accuracy

18. Create an Algorithm Develop an algorithm before writing a program
Use precise statements
Based in mathematics and logic
Clear and concrete language
Define a step-by-step process
Goal is solution to a problem

19. Use a Programming Language
A computer’s CPU uses machine language
Consists of binary values representing instructions
Not practical for human programmers
Assembly language
Low-level language closely tied to machine language
Once widely used, now only specialized use
High-level languages
Hundreds to thousands of languages in use
Much easier to use than assembly and machine language
Compiler provides automatic translation to machine language

20. Based on a Programming Model
The operating system (OS) presents the programming model
An OS is used on all but the smallest computers
Controls the hardware
Standardizes access to files, shared resources
May be console user interface or graphical (GUI) user interface
Console-based user interface
Called “command-line” access
Based on text serial input and output
Graphical user interface (GUI)
Based on point-and-click or touch screen and windowed interface
Event-driven, object-oriented model
Embedded systems may not have a user interface at all

21. The Compiler Approach A compiler is a translation program
Input is written using a programming language
Output is assembly language for one specific CPU instruction set
Assembler may be included or separate
Completes the translation into machine language
Linker
Combines translated program pieces with library pieces
Creates a complete, executable module
Operating system and loader
Loads module into main memory and starts execution
Process must be done again for each type of “host” system

22. The Interpreter Approach
Compiler creates an intermediate representation
Program is neither in high-level language, nor machine language
Instead, it is “virtual instructions” in an intermediate language
The virtual instructions are the same for all CPUs
Interpreter follows the virtual instructions
A different interpreter is needed for each CPU type
Benefits
A single compilation can theoretically be used on all computers
Presents a common programming model on multiple CPUs
Drawback
Interpreters are slower than compiled (“native”) programs

23. The “Just-In-Time” (JIT) Approach
Compiler
Creates an Intermediate Language (IL) representation
Runtime system
Does not interpret
Contains a “compiler” which completes compilation
Result is machine language produced just before execution
Best of both worlds
Code can be “Compiled once, Run anywhere” (e.g. Java, .NET)
Single programming model regardless of computer host
Program execution speed is comparable to native code

24. Specialized Programming Tools
Editor
Compiler
Assembler
Debugger
Support files
Libraries
Integrated development environment
Complete package of tools
Uses a “project-based” approach

25. Software Engineering
Waterfall model, iterative model, agile development
Processes to move from idea to product
Lifecycle management
Beginning-to-end product management
Includes program maintenance over time
Support and structure for working in teams
Coding standards
Change control
Project management
Human factors
“User friendly” design, ease of use

26. What is an Algorithm?
Unit 1: Algorithms

27. Software Development Method
Specify the problem requirements
Analyze the problem
Design the algorithm to solve the problem
Implement the algorithm as a program
Test and verify the completed program
Maintain and update the program

28. Analyzing the Problem Requires identifying the …
Inputs – the data available to work with
Outputs – the desired results
Including the format of the output
Additional requirements
Constraints

29. Producing the Algorithm
List of steps from beginning to end
Begin at step 1, have a specific step to End
Don’t try to get every detail at first
Use top-down design:
Break the problem into subproblems
Solve each subproblem individually
Similar to outlining a written paper
Use pseudo-code combined with flowcharting
Desk-check the algorithm

30. Convert the Algorithm to a Program
Implement the flowchart and pseudo-code as a program
Verify that the program compiles
Test the program
Create several test cases and verify the results
Test boundary conditions
Enter erroneous data intentionally
If the program behaves unexpectedly, back up
Double-check the algorithm, modify if needed
Double-check the program, modify if needed
Use debugging tools and techniques

31. Identify Variables Information in an algorithm is put into variables
A variable is the programming term describing the storage of a single datum or a collection of data.
In a program, the compiler will put the variables into memory
Each data item used in the algorithm should be given a name
Each name should be distinct and used for only one variable
Data types for variables include:
Integers: 0, 12, -53
Decimal numbers: 22.76, 193.1
Decimals in scientific notation 3.0x108
Character strings (in double-quotes) “Programming is fun!”

32. Simple Example: miles to kilometers
Problem statement “Convert a distance in miles to kilometers”
Identify the inputs dist_in_miles A decimal number representing a distance in miles
Identify the outputs dist_in_kms A decimal number representing the distance in kilometers

33. List the Steps to Solve the Problem
Break the problem into steps:
Input the dist_in_miles
Convert dist_in_miles to kilometers
Output the dist_in_kms
As you can see, step 2 is not precise, because it does not specify how to do the conversion. This is not yet a complete algorithm.

34. What is the Formula for Step 2?
One mile is equal to approximately equal to km
A number of miles can be converted to kilometers by multiplying by 1.609
The formula is:
dist_in_km = dist_in_mi × 1.609

35. Algorithm to Convert mi to km
Input the dist_in_miles
Convert dist_in_miles to kilometers
Multiply dist_in_miles by 1.609
Put the result in dist_in_kms
Output the dist_in_kms
End
This algorithm accomplishes the task, but it is not user-friendly. We need to add some human factors to the algorithm.

36. An Improved Algorithm Output “Convert miles to kilometers”
Output “Please enter the distance in miles”
Input dist_in_miles
Convert dist_in_miles to kilometers
Multiply dist_in_miles by 1.609
Put the result in dist_in_kms
Output “The distance in kilometers is ”
Output dist_in_kms
End
As you can see, creating a good algorithm requires substantial effort and attention to details

37. An Algorithm to List #s < 10
Output “List of Numbers less than 10”
Put 1 in number
Output number
Add 1 to number
If number is less than 10, go back to step 3
End
Notice this algorithm has no inputs, only one variable, “number”

38. An Algorithm to List Odd #s < 10
Output “List of Odd Numbers less than 10”
Put 1 in number
If number is even, skip to step 5
Output number
Add 1 to number
If number is less than 10, go back to step 3
End
Is this an algorithm? Is step 3 sufficiently precise?

39. An Algorithm to List Odd #s < 10
Output “List of Odd Numbers less than 10”
Put 1 in number
If number divided by 2 has remainder 0, go to step 5
Output number
Add 1 to number
If number is less than 10, go back to step 3
End
Now we have precise instructions which can be followed!