lecture 1 course intro

8/21/2019 Lecture 1 Course Intro

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Lecture 1

Programming

Fundamental


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Software

The intermediary between you (the user)and the hardware

Operating system (OS) see the next page

Windows, OS X, LinuxApplication programs

End-user applications Word processor, etc.

Matlab, etc. Application development software

(programming languages)

C, Matlab (sort of), Python, Java, FORTRAN, etc.


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Operating System (OS)

A program that: Acts as an intermediarybetween

hardware and applicationsoftware

Provides a consistent, stable wayfor applications to interact withhardware APIs, so you dont have to do it all

yourself

Examples: Windows XP/Vista

Linux

http://en.wikipedia.org/wiki/File:Operating_system_placement.svg


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Not correct

Correct

Create/Edit

source files(your program!)

Program Development

Compile

source files

Link

compiled files

Load

executable file

Run

your program!

Test

Repeat process


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Method for Developing a Program

1. Define the problem:

State the problem you are trying to solve in clear andconcise terms.

2. List the inputs and the outputs Inputs: information needed to solve the problem

Outputs: what the algorithm will produce as a result

3. Describe the steps needed to convert or manipulate theinputs to produce the outputs (develop the algorithm)

Begin at a high-level first

Refine (subdivide the high-level) steps until they areeffectively computable operations.

4. Test the algorithm:

choose data sets, and verify that your algorithm works!

Note: these steps are to be done BEFOREyou write any program code!


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Structured Programming

Sequence

Selection

IF

IFELSE SWITCH

Repetition

WHILE DOWHILE

FOR

Flowchart constructs


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Algorithm

What is an algorithm?

A recipe

A procedure

Definition:

well-ordered collection of unambiguous and

effectively computable operations, that when

executed, produces a result and halts in a finite

amount of time.


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Characteristics of an Algorithm

Well-ordered:

the steps are in a clear order

Unambiguous:

the operations described are understood by a

computing agent without further simplification

Effectively computable:

the computing agent can actually carry out

the operation


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Pseudocode

natural language-like statements that preciselydescribe the steps of an algorithm

Statements that describe actions

Focuses on the logicof the algorithm Avoids language-specific elements

Written at a level so that code can be generatedalmost automatically from each statement

Steps are numbered Subordinate numbers and/or indentation are used for

dependent statements in selection and repetitionstructures


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Flowcharts - 1

Flowcharts

A graphical tool that diagrammaticallydepicts

the steps and structure of an algorithm or

programSymbol Name/Meaning Symbol Meaning

ProcessAny type of internal

operation: data transformation,

data movement, logic operation,

etc.

Connectorconnects sections

of the flowchart, so that the

diagram can maintain a smooth,

linear flow

Input/Output

input or outputof data

Terminal

indicates start orend of the program or algorithm

Decisionevaluates a condition

or statement and branches

depending on whether the

evaluation is true or false

Flow linesarrowsthat

indicate the direction of the

progression of the program


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Flowchart Constructs - Sequence and Selection

from Deitel & Deitel, 6th ed., p. 122Control Structures


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Flowchart Constructs - Repetition

from Deitel & Deitel, 6th ed., p. 122

Control Structures


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Example:

Obtain a series of positive numbers from the keyboard, and

determine and display their sum. Assume that the user types the

sentinel value -1 to indicate "end of data entry"

Define the problem

Statement pretty well defines the problem

List inputs and outputs

inputs: number entered from keyboard

outputs: sum of number


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Example:

Obtain a series of positive numbers from the keyboard, and

determine and display their sum. Assume that the user types the

sentinel value -1 to indicate "end of data entry"

Develop the algorithm

High-level first, then refine:

Does this work?

1. Start

2. Declare variables: ________

3. Repeat while number not equal to -1

3.1. get number3.2. add to sum

4. Display sum


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Example:

1. Start

2. Declare variables: num, sum

3. while numnot equal to -1, continue doing:

3.1. Display prompt Enter positive number

3.2. Read number from the keyboard3.3. Display number entered

3.4. add to sum

4. Display sum

1. Start

2. Declare variables: ________3. Repeat while number not equal to -1

3.1. get number

3.2. add to sum

4. Display sum

Develop the algorithm,cont.

Refine

Are we there yet?


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Example:

1. Start

2. Declare variables: num, sum3. while numnot equal to -1, continue doing:


3.2. Read number from the keyboard

3.3. Display number entered

3.4. if num less than zero, then3.4.1 continue

3.5. add to sum

4. Display sum

Develop the algorithm,cont. Add a test to exclude negative numbers

Are we there now?


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Flowchart StartDeclare variables: num, sum

Intialize variables: num = 0, sum = 0

Display "Enter

positive integer"if num ! = -1

if num < 0

Read num from

keyboard

Display num

Yes

Yes

sum = sum + num

Display sum

Stop

No

No

1. Start

2. Declare variables: num, sum

3. while numnot equal to -1, continue doing:


3.2. Read number from the keyboard

3.3. Display number entered

3.4. if num less than zero, then

3.4.1 continue

3.5. add to sum

4. Display sum

Test the algorithm!


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Structure of a C Program

A formal letter has a

structure

So does a program in C

Burford Furman

Professor

Dept. of Mech. and Aero. Eng

San Jos State University

San Jose, CA 95192-0087

July 20, 2009

Dear Prof. Furman,

Im writing you to see if I can get into ME 30

Sincerely,

Jane Student

Title block

Date

Salutation

Body

Closing

Signature


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C Code

Programmers block

Pre-processor directive

Declare and initialize

variables

While loop

(repetition structure)

Main function (statements go between { } )

return statement


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Programmers Block

Include important information (comments)to documentthe program: Title

Date

Author

Description

Inputs/Outputs

Algorithm

Revision history

Add comments using one of two methods:1./*put comment between */ (note: traditional C)

2.//comment (note: single line only)


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# include (pre-processor directive)

Includes a library file for standard io

functions for things like printing, etc.


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main() function

Your program needs amain() function

Statements go between

the braces { }

main() ends with thereturnkeyword and

usually the value zero

If main() runs

successfully, it returns

a value of zero


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Declare and initialize variables

Variables must be declared beforeyou can use them


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while() Repetition Structure

Full program

while (condi t ion

)repeat statements

between { }

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