Difference between revisions of "KTurtle/C3/Control-Execution/English"

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'''Loop'''
 
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Revision as of 15:58, 9 January 2013

Visual Cue Narration
Slide Number 1

Hello Everybody.

Welcome to this tutorial on Control Execution in KTurtle

Slide Number 2

Learning Objectives

In this tutorial, we will learn
  • 'while' loop and
  • 'for' loop
Slide Number 3

System Requirement

To record this tutorial I am using,

Ubuntu Linux OS Version 12.04

KTurtle version 0.8.1 beta.

Slide Number 4

Pre-requisites

We assume that you have basic working knowledge of Kturtle.

If not,

for relevant tutorials, please visit our website. http://spoken-tutorial.org

Switch to KTurtle Application

Dash home >>Search bar appears>>

In the Search bar type KTurtle

Let's open a new KTurtle Application.

Click on Dash home. The Search bar appears.

In the Search bar, type KTurtle.

Click on the option. KTurtle Application opens.

Let me first explain about what is control execution?
Slide Number 5

Control execution

Control execution is controlling the flow of a program.

Different conditions are used to control program execution.

Slide Number 6

Loop

Loop is a block of code is executed repeatedly till a certain condition is satisfied.

Eg. “while” loop and “for” loop

Let's begin the tutorial with “while” loop
Slide Number 7

“while” loop

In the “while” loop, the code inside the loop repeats till boolean evaluates to 'false'.
Slide Number 8

Syntax of “while” loop

Let me explain the structure of “while” loop.

while loop condition { 

 do something

with loop increment variable }

I already have the code in a text editor.
#program to print a series of multiples 3 upto 30

reset

$x=0

message"In while loop, code inside the loop repeats till boolean evaluates false"

while $x<30 {

$x=$x+3

fontsize 15

forward 20

print $x }

Let me copy the program from text editor and paste it into KTurtle editor


Please pause the tutorial here and type the program into your KTurtle editor. Resume the turtorial after typing the program

Let me zoom into the program text it may possibly be a little blurred.
Let me explain the code.
Highlight # # sign comments a line written after it.

It means, this line will not be executed while running the program.

Highlight reset reset command sets “Turtle” to its default position.
Highlight $x $x=0 initialises the value of variable x to zero.
Highlight message" " Message in a program is given within double quotes after the keyword message " "

“message” command takes “string” as input. It shows a pop-up dialog box containing text from the string.

Highlight while $x<30 while $x<30 checks the “while” condition.
Highlight $x=$x+3 $x=$x+3 increments the value of variable $x by 3
Highlight fontsize 15 fontsize 15 sets the font size used by print command.

Fontsize takes number as input, set in pixels.

Highlight forward 20 forward 20 commands “Turtle” to move 20 steps forward on the canvas.
Highlight print $x print $x displays the value of variable x on the canvas.
Run the program Let me click on the “Run” button to run the program.

A message dialog box pops up. Let me click OK.

Run the program Multiples of 3 from 3 to 30 are displayed on the canvas.

“Turtle” moves 20 steps forward on the canvas.

Let's next work with “for” loop
Slide Number 9

"for" loop

“for” loop is a counting loop.

Every time the code inside “for” loop is executed,

variable value is incremented, till it reaches the end value.

Slide Number 10

Syntax of “for” loop

Let me explain the structure of “for” loop.

for variable = start number to end number { Statement}

Clear the editor and canvas Let me clear the current program.

Let me type clear command and run to clean the canvas.

#program print to sum of first 15 natural numbers

reset'

$r=0

for $x= 1 to 15{

$r=$x*($x+1)/2

fontsize 18

print $r

forward 15 }

go 10,250

wait 2

print "Sum of first 15 natural numbers ="+$r

Let me copy the program from text editor and paste it into KTurtle editor


Please pause the tutorial here and type the program into your KTurtle editor.

Resume the turtorial after typing the program.

Let me zoom into the program text it may possibly be a little blurred.
Let me explain the code.
Highlight # # sign comments a line written after it.
Highlight reset reset command sets “Turtle” to default position.
Highlight $r=0 $r=0 initialises the value of variable r to zero.
Highlight for $x= 1 to 15 for $x= 1 to 15 checks “for” condition from 1 to 15.
Highlight $r=$x*($x+1)/2 $r=$x*($x+1)/2 calculates the value of variable r.
Highlight fontsize 18 fontsize 18 sets the font size used by print command.
Highlight print $r print $r displays the value of variable r on the canvas.
Highlight forward 15 forward 15 commands Turtle to move 15 steps foward on the canvas.
Highlight go 10,250 go 10,250 commands Turtle to go 10 pixels from left of canvas and 250 pixels from top of canvas.
Highlight wait 2 “Turtle” displays all print commands without any time gap.

“Wait 2” command makes Turtle to “wait” for 2 seconds before executing next command.

print "Sum of first 15 natural numbers ="+$r “print” command displays the “string” within double quotes and also displays variable $r.
Run the program Let me click the “ Run” button to run the program.

A series of sum of first 15 natural numbers and sum of first 15 natural numbers is displayed on the canvas.

Turtle moves 15 steps forward on the canvas.

With this we come to end of this tutorial.
Slide Number 11

Summary

Let us summarize.

In this tutorial we have learnt to use,

  • “while” loop and
  • “for” loop
Slide Number 12

Assignment

As an assignment I would like you to write programs to evaluate
  • Multiples of 2 using “while” loop
  • Multiplication table of a number using “for” loop
Slide number 13 Acknowledgement

Watch the video available at this URL

http://spoken-tutorial.org/What is a Spoken Tutorial

It summarises the Spoken Tutorial project

If you do not have good bandwidth, you can download and watch it

Slide Number 14 The Spoken Tutorial Project Team :

Conducts workshops using spoken tutorials

Gives certificates to those who pass an online test

For more details, please write to

contact@spoken-tutorial.org

Slide number 15 Spoken Tutorial Project is a part of the Talk to a Teacher project

It is supported by the National Mission on Education through ICT, MHRD, Government of India

More information on this Mission is available at this link http://spoken-tutorial.org/NMEICT-Intro ]

This is Madhuri Ganpathi from IIT Bombay signing off Thank you for joining

Contributors and Content Editors

Madhurig

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