1. Introduction to Programming
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2. Main Menu What is a Computer Program?
The Main Steps in Developing a Program
Basic Elements of Any Program
Types of Errors
Basic Control Structures
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3. Home
Pseudocode
Pseudocode consists of English like statements that describe the processing steps of a program in paragraph form. It is an informal language that is easy and user friendly to use. It is not an actual programming language and are not executed on computers. They can help you “think out” a program before attempting to write it in a programming language.
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4. Home
Algorithms
A computer is only a tool that can do what it is specifically told to do. We can direct the computer to do what we want by specifying our needs in a discrete step-by-step manner.
An algorithm must be developed, which is a step-by-step procedure to solve a problem.
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5. Algorithms Home An algorithm must meet the following requirements:
Use operations from only a given set of basic operations
Produce the problem solution, or answer, in a finite number of such operations.
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6. Home High Level Languages
There are many programming languages –some examples are Basic, c, c++, Visual Basic, Java, Pascal. These are high level languages which are closer to human languages. Programs can also be written in low level languages such as assembly language and is closer to the language of the computer.
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7. What is a computer Program?
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What is a computer Program?
A program is an organized list of instructions that when executed causes the computer to behave in a predetermined manner. It is a step-by-step list of instructions written in a particular computer programming language.
Without programs, computers are useless.
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8. Main Steps in Developing a Program
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Main Steps in Developing a Program
Define the problem
Outline the solution
Develop the outline into an algorithm
Test the algorithm for correctness
Code the algorithm into a specific
programming language
6. Run the program on the computer
Document and maintain
the program
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9. Home The Basic Elements of any Program
The basic elements of any program are:
Input
Processing
Output
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10. Home
Input
This is entering or sending data to the computer. The most frequent way of entering data is by using the keyboard.
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11. Home
Processing
The processor or microprocessor is the part of the computer that reads, interprets and executes the program instructions. Processors are integrated circuits that contain transistors and other electronic components.
It is a small chip that functions as the “brain” of the computer. The processor is also called the Central Processing Unit (C.P.U)
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12. Home
Output
Sending or displaying data to the user. Common output devices includes the monitor and the printer.
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13. What Have You Learnt? End Previous Page Home Page Next Page
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14. Click on the correct answer:
Quiz
Click on the correct answer:
A set of English like statements that is used as an informal language is called:
Algorithm
Psuedocode
Computer program A B
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15. Click on the correct answer:
Quiz
Click on the correct answer:
Which of the following is NOT a high level language?
Basic
Assembly
C++ A B C
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16. Click on the correct answer:
Quiz
Click on the correct answer:
The basic elements of any program are:
Input, storing, processing
Input, storing,output
Input, processing, output A B C
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17. Is the following statement true or false?
Quiz
Is the following statement true or false?
Click on true if the statement is correct or false if it is incorrect.
A computer program is a step-by-step list of instructions written in a particular computer programming language.
True
False
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18. End of Quiz! end Previous Page Home Page Next Page
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19. Types of Errors Semantic Errors Syntax Errors Logic Errors
Errors that programmers usually make includes:
Semantic Errors
Syntax Errors
Logic Errors
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20. Semantic Errors
This is where meaning of the language is not obeyed. For example, what the words really say or what functions are requested in the command.
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21. Syntax Errors
Violations of the language. Syntax error refers to the spelling and grammar of a programming language. The particular programming language used expects words entered in a specific form. The expected form is called the syntax.
Each program defines its own syntactical rules that control which words the computer understands, which combinations of words are meaningful and what punctuation is necessary.
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22. Logic Errors
A logic error occurs when a step in the program logic is incorrect e.g. an average program will produce a wrong answer if the sum of the numbers is divided by a number other than the total count of the numbers.
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23. Basic Control Structures
The basic control structures are:
Simple Sequence
If-Then-Else
Do While
The ability to express a problem solution using only three basic patterns of control is called structured programming.
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24. Simple Sequence Programs
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25. Simple Sequence Control Structure
Represents the computer’s ability to execute instructions in step-by-step, sequential manner.
It is the simplest and most frequently used of the three basic control structures.
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26. FLOWCHARTS
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27. Simple Sequence End Proceed down Orange Street for two miles.
Turn right on Duke Street.
Proceed on Duke Street.
At fork, take Main Street to the left.
Proceed two blocks.
Store is on the left (77 Main Street.
An example of a simple sequence set of instructions not involving the use of a computer is the steps you might give a friend to get to a store. The steps must be followed in a sequential manner otherwise your friend may get lost and never find the store.
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28. Flowchart
A program flowchart is a pictorial representation of an algorithm.
Start
Proceed down orange
street for two miles
Turn right on duke street
Stop
At fork, take main street
to the left
Store is on the left
(77 Main Street)
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Proceed two blocks
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29. Simple Sequence A simple wake up algorithm: Get out of bed Brush teeth
Program
Flowchart
A simple wake up algorithm:
Get out of bed
Brush teeth
Eat breakfast
Take shower
Get dressed
Start
Brush teeth
Eat Breakfast
Take shower
Get dressed
Stop
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30. Flowchart Symbols
Start – Every algorithm must have one entry point (Start) and one exit point (stop).
These are indicated by the ellipsis symbols, called terminal interrupt symbols.
Start
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Stop
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31. Flowchart Symbols
Input/output Symbol – Reading data from an input medium or writing data to an output medium.
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32. Flowchart Symbols
Process symbol – Shows any processing steps. It represents an operation or group of operations causing change in value, form or location of data.
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33. Flowchart Symbols
Flow Line - shows sequence of operations arrowheads are required if linkage is not top-to-bottom or left-to-right.
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34. Flowchart Symbols
Decision Symbol – shows decision-making operation, usually based on a comparison, that determines which of two or more alternative paths should be followed.
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35. Flowchart Symbols
Connector - Shows exit to, or entry from, another part of the flowchart; if the to or from step is another page, a page reference should be stated.
FROM PAGE 3 B3 c2
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36. Annotation symbol – Gives additional explanation; comments.
Flowchart Symbols
Annotation symbol – Gives additional explanation; comments.
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37. Flowchart Symbols
Preparation symbol – An operation performed on the program itself for control, initialization, overhead, or cleanup. E.g. to set a switch, to place a limit value in the loop control variable and to initialize an accumulator.
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38. Flowchart Symbols
Predefined Process – Used to identify a series of steps shown another flowchart.
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39. Variables
Variables are data items whose values may change, or vary, during processing.
Variable names are created to represent, or refer to, these data items. They are used to give names to lactations where data should be stored.
Click for Hint
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40. Variable Names
Choose variable names that are appropriate and gives an indication of what will be stored. Shorten names where possible.
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41. Simple Sequence Structure
The Simple Sequence Structure represents the computer’s ability to execute instructions in a step-by-step, sequential manner.
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42. Solution – Example 1 End Program Flowchart Pseudocode Start
Print “Enter FARENHEIT value”
Read farenht
celsius = (fareneht – 32) * 5/9
Print farenht, celsius
stop
Print “Enter FARENHEIT value”
Read farenht
celsius = fareneht – 32) * 5/9
Print farenht, celsius
Stop
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43. Example 1 – In Basic Language
Print “Enter FARENHEIT value” input farenht celsius = (fareneht – 32) * 5/9 Print “The farenheit temperature is: “; farenht Print “The celsius temperature is: “; celsius End
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44. Problem- Using Simple Sequence
Example 2
A store needs a computer program to prepare a monthly bill for each customer. For simplicity, assume that each customer purchases (at most) one type of item each month. For each purchase, there will be four inputs: customer name, item, quantity purchased, and price. The output will be the customer’s monthly bill after a 10 per cent discount is taken before taxes and a 5 % sales tax is added.
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45. Solution – Example 2
Pseudocode Start Print “Enter name, item, quantity, and price” Read name, item, qty, price amtod = qty * price discount = amtod * 0.10 subbill = amtod – discount taxes = subbill * 0.05 bill = subbill * taxes Print name, item, bill stop
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46. End Solution – Example 2 Program Flowchart Previous Page Home Page
subbill = amtod - discount
Start
Print “Enter name item, quantity and price”
discount = amtod * 0.10
taxes = subbill * 0.05
Read name item, qty, price
amtod = qty * price
bill =subbill + taxes
Print name, item, bill
Stop
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47. Program in Basic
Print “Enter name, item, quantity, and price” Input name, item, qty, price amtod = qty * price discount = amtod * 0.10 subbill = amtod – discount taxes = subbill * 0.05 bill = subbill * taxes Print name, item, bill end
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48. Selection Control Structure
If-Then- Else
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49. IF-THEN-ELSE CONTROL STRUCTURE
The IF-THEN- ELSE control structure indicates that at a particular time in processing, a choice between alternative paths, or sequence of instructions is to be made.
It is a conditional statement that causes execution of some statement depending on the truth value of a certain condition. If the condition is true, then the statement (s) after “then” are executed. If the statement is false then the statement (s) after “else” are executed provided that the else clause is present.
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50. IF-THEN-ELSE CONTROL STRUCTURE
Example 1 - Flowchart
Example 1 - Pseudocode
If rain is falling then
take umbrella
Endif
Start
Rain is falling? No
Yes
Take Umbrella
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Stop
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51. IF-THEN-ELSE CONTROL STRUCTURE
Example 2 - Flowchart
Example 2 - Pseudocode
If rain is falling then
take umbrella
Else
don’t take umbrella
Endif
Start
Rain is falling? No
Yes
Don’t take
Umbrella
Take Umbrella
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Stop
End
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52. Selection Control Structure Do while Control Structure Else
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53. Do While Control Structure
The “Do While” structure is a repetition statement that allows you to specify that an action is to be repeated while some condition remains true.
For example:
while there are more items on my shopping list
Purchase next item and cross it off my list.
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54. End Do While Control Structure Previous Page Home Page Next Page
Print “Enter two numbers, (Enter 999 to end program):
Start
Read x
Read y
Do While
Control Structure
X = 999 ?
Yes
Stop No
X > y ?
Print “The first number is greater” No
Yes
Read x
Read y
Print “The second number is greater”
Print “Enter next two numbers, (Enter 999 to end program):
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Print x, y
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55. Do While Control Structure
Start
Print “Enter two numbers, (Enter 999 to end program):”
Read x
Read y
do while x not equal to 999
if x > y then
print “The first number is greater”
else
print “The second number is greater”
endif
Print x, y
Print “Enter next two numbers, (Enter 999 to end program):”
Enddo
Stop
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in Basic
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56. Very Good. That is Correct!
Back to Quiz
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57. Sorry! That is not Correct.
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58. Created By: Natalee N. Nembhard Thanks for Using the Program
Created By: Natalee N. Nembhard Thanks for Using the Program! © Copyright 2010
EXIT
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