# Introduction%20to%20Programming - PowerPoint PPT Presentation

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## Introduction%20to%20Programming

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### Rattapoom Waranusast Department of Electrical and Computer Engineering Faculty of Engineering, Naresuan University – PowerPoint PPT presentation

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Title: Introduction%20to%20Programming

1
Introduction to Programming
305171 Computer Programming Rattapoom
Waranusast Department of Electrical and Computer
Engineering Faculty of Engineering, Naresuan
University
2
What is Algorithm
• Algorithm is a process or a set of rules to be
followed in calculations or other problem-solving
operations.
• The instructions should be simple and clear
enough so that each step can be done without
confusion.

3
Example
• This is an example of an algorithm for sorting
cards with colors on them into piles of the same
color
• Pick up all of the cards.
• Pick a card from your hand and look at the color
of the card.
• If there is already a pile of cards of that
color, put this card on that pile.
• If there is no pile of cards of that color, make
a new pile of just this card color.
• If there is still a card in your hand, go back to
the second step.
• If there is not still a card in your hand, then
the cards are sorted, you are done.

4
Real-world Algorithm
5
Algorithm?
6
What is A Program?
• A program is a very specific set of steps and
rules.
• A program is an implementation of an algorithm in
a particular language to run on a computer
(usually a particular kind of computer)
• Algorithm what we want to do
• Program what we actually did
• The process of creating a program is called
programming.
• Programming is breaking a task down into small
steps and rules.

7
Lets do some Examples
• Put these words in alphabetical order apple,
zebra, abacus
• Count the number of words in these sentences
• Programming really can be fun.
• John,do it again.
• Some people just love to type really short
lines, instead of using the full width of the
page.

8
Flowchart
• A flowchart is a diagram that depicts the flow
of a program.

9
Basic Flowchart Symbols
• Terminals
• represented by rounded rectangles
• indicate a starting or ending point

Terminal
10
Basic Flowchart Symbols
• Input/Output Operations
• represented by parallelograms
• indicate an input or output operation

Input/Output Operations
11
Basic Flowchart Symbols
• Processes
• represented by rectangles
• indicates a process such as a mathematical
computation or variable assignment

Process
12
Stepping Through the Flowchart
• Variable Contents Hours ? Pay Rate ? Gross
Pay ?

13
Stepping Through the Flowchart
How many hours did you work?
• Variable Contents Hours ? Pay Rate ? Gross
Pay ?

14
Stepping Through the Flowchart
How many hours did you work? 40
• Variable Contents Hours 40 Pay Rate ? Gross
Pay ?

15
Stepping Through the Flowchart
How many hours did you work? 40
How much do you get paid per hour?
• Variable Contents Hours 40 Pay Rate ? Gross
Pay ?

16
Stepping Through the Flowchart
How many hours did you work? 40
How much do you get paid per hour? 300
• Variable Contents Hours 40 Pay Rate
300 Gross Pay ?

17
Stepping Through the Flowchart
How many hours did you work? 40
How much do you get paid per hour? 300
• Variable Contents Hours 40 Pay Rate
300 Gross Pay 12000

18
Stepping Through the Flowchart
How many hours did you work? 40
How much do you get paid per hour? 300
12000
• Variable Contents Hours 40 Pay Rate
300 Gross Pay 12000

19
Stepping Through the Flowchart
How many hours did you work? 40
How much do you get paid per hour? 300
12000
• Variable Contents Hours 40 Pay Rate
300 Gross Pay 12000

20
Four Flowchart Structures
• Sequence
• Decision
• Repetition
• Case

21
Sequence Structure
• a series of actions are performed in sequence
• The pay-calculating example was a sequence
flowchart.

22
Decision Structure
• One of two possible actions is taken, depending
on a condition.
• In the flowchart segment below, the question is
process A is performed. If the answer is yes,
then process B is performed.

Yes
No
23
Repetition Structure
• A repetition structure represents part of the
program that repeats. This structure is commonly
known as a loop.
• In the flowchart segment, the question is x lt
A is performed. The question is x lt y? is asked
again. Process A is repeated as long as x is less
than y. When x is no longer less than y, the
repetition stops and the structure is exited.

24
Case Structure
• One of several possible actions is taken,
depending on the contents of a variable.
• The structure below indicates actions to perform
depending on the value in years_employed.

25
Connector
• Sometimes a flowchart will not fit on one page
length.
• A connector (represented by a small circle)
allows you to connect two flowchart segments on
the same page.
• The A connector indicates that the second
flowchart segment begins where the first segment
ends.

26
Modules
• The position of the module symbol indicates the
point the module is executed.
• A separate flowchart can be constructed for the
module.

27
Other common Symbols
• Off-page connector
• Used to connect remote flowchart portion on
different page
• Comment
• Document
• Used to represent a print out
• Database
• Used to represent a database

28
Pseudocode
• Pseudocode is a compact and informal high-level
description of a computer programming algorithm
that uses the structural conventions of a
programming language, but is intended for human
typically omits details that are not essential
for human understanding of the algorithm, such as
variable declarations, system-specific code and
subroutines. (Wikipedia)

29
Pseudocode
• Pseudocode generally does not actually obey the
syntax rules of any particular language.
• There is no systematic standard form.
• Pseudocode may therefore vary widely in style,
from a near-exact imitation of a real programming
language at one extreme, to a description
approaching formatted prose at the other.

30
A Guideline for Pseudocode
• Write only one statement per line
• Capitalize initial keyword
• Indent to show hierarchy
• End multiline structures
• Keep statements language independent

31
Example
• BEGIN Procedure_NetCalc
• IF taxes gt 0
• net grossPay taxes
• ELSE
• net grossPay
• ENDIF
• WRITE name, net
• END Procedure_NetCalc

32
Decision Structure
• Pseudocode
• IF Y gt 3
• X 5
• ELSE
• X 10
• ENDIF

33
Repetition Structure and Module
• BEGIN
• count 0
• WHILE count lt 10
• DO Process
• ENDWHILE
• WRITE The End
• END
• BEGIN Process