KTurtle/C3/Common-Errors-in-KTurtle/English

Visual Cue	Narration
Slide Number 1	Hello everybody. Welcome to this tutorial on Common Errors in KTurtle.
Slide Number 2 Learning Objectives	In this tutorial, we will learn about Syntax errors Runtime errors Logical errors
Slide Number 3 System Requirement	To record this tutorial I am using, Ubuntu Linux OS v. 12.04. KTurtle v. 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
Slide Number 5 Definition of Error	Let's first define, What is an error ? Error is a mistake in a program that produces an incorrect or unexpected result.
	First I will explain about "Types of errors".
Slide Number 5 Syntax Errors	A syntax error is a violation of grammatical rules, of a programming language. Compilation fails when a program has syntax errors. Syntax errors are easy to find and fix. For Example: Unmatched parentheses, square brackets and curly braces. Use of variable that has not been declared. Missing quotes in strings.
Switch to KTurtle Application Dash home >>Search bar appears>> In the Search bar type KTurtle Click on the KTurtle icon.	Let's open a new KTurtle Application. Click on Dash home. The Search bar appears. In the Search bar, type KTurtle. Click on the KTurtle icon.
	Let's begin the tutorial with some types of syntax errors.
	I already have a program in a text editor.
reset $a=ask "enter any number and click Ok" $r = ask "enter any number and click ok" $n = ask "enter any number and click ok" $T = $a*($r^$n)*($r^-1) print $T	I will Copy the program into Kturtle Editor. Pause the tutorial and type the program your into KTurtle editor Resume the tutorial after typing the program.
Zoom text	Let me zoom into the program text. It may possibly be a little blurred.
Comment code	To explain error in the program, I will comment the code.
Highlight $a=ask "enter any number and click Ok"	Here, I will comment the line $a=ask "enter any number and click Ok"
Run the program	Let's Click on Run button to run the program Complier shows the following error, The variable "$a" was used without first being assigned to a value.
Highlight Line number 2	Error is in line number 2.
Syntax error	This is syntax error. It occured, as the variable 'a' was not declared.
Highlight $a=ask "enter any number and click Ok" Remove the comment	So I will go to line number 2 and remove the comment.
Run the program	Let's run again press F5 key to run the program We see that the program runs without errors.
	Next let's look at another error.
	I already have a program in a text editor.
reset $degree=ask "enter an angle value and click OK" $radian=(pi/180)*$degree go 50,50 print "Value in radians is"+ " " +$radian spritehide	I will copy the program into Kturtle Editor Please pause the tutorial and type the program your into KTurtle editor Resume the tutorial after typing the program.
Zoom text	Let me zoom into the program text. It may possibly be a little blurred.
Highlight$radian=(pi/180)*$degree	Value of "pi" is predefined in KTurtle.
Highlight $	Let's delete $ sign in the program.
Run the program	Let's Click on Run button to run the program. Complier shows the following error, you cannot put “=” here
Highlight Line number 2	Error is in line number 2.
Show error	This syntax error occured, as there is no container of variables.
Replace $ sign	Let's replace the $ sign and run again. Program runs properly
Highlight "Value in radians is"	Let's remove one of the quotes of the string.
Run the program	Let's click on Run button to run the program Complier shows the following error, text string was not properly closed, expected a double quote “ ” to close the string.
Highlight Line number 5	Error is in line number 5.
Replace the quotes	So I will go to line number 5 and replace the quotes. press F5 key to run the program. Program runs without errors. This way you can find the line at which error has occured, and correct it.
	Let's now learn about runtime errors.
Slide Number 6 Runtime errors	Run-time error occurs during the execution of a program. It may crash the program when you run it. Runtime errors are commonly due to wrong input from the user. Compiler cannnot find these errors. For example: Trying to multiply or divide by a variable that contains no value. Run a loop without a terminating condition or increment value.
	I already have a program in a text editor.
reset $a=ask "enter a number for 'a' and click Ok" $r = ask "enter a number for 'r' and click OK" $d=$a/$r print $d	I will copy the program into Kturtle Editor. Pause the tutorial and type the program into your KTurtle editor Resume the tutorial after typing the program.
Zoom text	I will zoom into the program text. It may possibly be a little blurred.
Run the program	Let's click on the Run button to run the program. Complier does not show any error. Let's enter 5 for 'a' and click OK enter 0 for 'r' and click OK Here we get a runtime error, “ you tried to divide by zero”
Highlight Line number 4	Here error is in line number 4.
Run time error	This error occurs as we cannot divide a number with zero.
	Next we will learn about logical errors.
Logical errors	Logical error is a mistake in a program's source code that results in incorrect or unexpected behavior. For example, Assigning a value to the wrong variable. Multiplying two numbers instead of adding.
	I already have a program in a text editor.
reset $x=30 message"In while loop, code inside the loop repeats till boolean evaluates false" while $x>20 { $x=$x+1 fontsize 15 forward 20 print $x }	I will copy the program into Kturtle Editor Pause the tutorial and type the program into your KTurtle editor Resume the tutorial after typing the program.
Zoom text	Let me zoom into the program text. It may possibly be a little blurred.
Run the program Highlight “ while” loop condition	Now click on the Run button to run the program. Complier does not show any error. Loop goes into an infinite loop. We see that “while” loop prints numbers from 31 and it is still printing. This is a logical error. In this “while” condition x is greater than 20, but the variable x is always greater than 20 So the loop never terminates.
Abort the process	I will click on Abort button to abort the process.
Change $x=$x+1 to $x=$x-1	Let's Change $x=$x+1 to $x=$x-1. Run again. program runs properly. Loop terminates after printing values from 29 to 20.
With this we have come to the end of this tutorial. let us summarise.
Slide Number 9 Summary	In this tutorial we have learnt, errors and types of errors such as Use of variable that has not been declared. Missing quotes in strings. Errors related to print command Runtime errors Logical errors
Slide Number 10 Assignment	As an assignment I would like you to find errors in the given programs-
Assignment 1	reset $x=3 $y=3 if $x==$y print"they are equal" else { print "they are not equal"}
Assignment 2	program to find the nth term and sum of n terms in GP reset $x=ask "enter value for x and click Ok" $y = ask "enter value for y and click Ok" $g =sqrt ($x*$y) print "Geometric mean is ="+
Assignment 3	reset learn sum $x { {$r=0 for $i= 1 to $x{ return $r} } print
Slide number 11 Acknowledgement	Watch the video available at 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 12	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 13	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 http://spoken-tutorial.org/NMEICT-Intro ] This is Madhuri Ganpathi from IIT Bombay Thank you for joining

Contributors and Content Editors

Arya Ratish, Madhurig