Difference between revisions of "KTurtle/C3/Common-Errors-in-KTurtle/English"

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'''Learning Objectives'''
 
'''Learning Objectives'''
 
||In this tutorial, we will learn about
 
||In this tutorial, we will learn about
−
* Syntax errors  and
+
* Syntax errors   
  
 
* Runtime errors
 
* Runtime errors
 +
 +
* Logical errors
 
|-
 
|-
 
|| Slide Number 3
 
|| Slide Number 3
Line 30: Line 32:
 
for relevant tutorials, please visit our website.  
 
for relevant tutorials, please visit our website.  
 
http://spoken-tutorial.org
 
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.
 
|-
 
|-
 
||
 
||
Line 90: Line 99:
 
It may possibly be a little blurred.
 
It may possibly be a little blurred.
 
|-
 
|-
−
||
+
||Comment code
−
||To explain error in the program, I will delete part of the code.
+
||To explain error in the program, I will comment the code.  
 
|-
 
|-
 
||Highlight  
 
||Highlight  
  
 
'''$a=ask "enter any number and click Ok"'''  
 
'''$a=ask "enter any number and click Ok"'''  
−
||Here, I will delete the line '''$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
 
||Run the program
Line 105: Line 114:
 
'''The variable "$a" was used without first being assigned  to a value.'''
 
'''The variable "$a" was used without first being assigned  to a value.'''
 
|-
 
|-
−
||Replace the deleted line
+
||Highlight Line number 2
−
||I will replace the deleted line '''$a=ask "enter any number and click Ok"'''
+
||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
 
||Run the program
Line 116: Line 133:
 
|-
 
|-
 
||
 
||
−
||Next let's look at another type of error.
+
||Next let's look at another error.
 
|-
 
|-
 
||
 
||
Line 146: Line 163:
 
|-
 
|-
 
||Highlight $
 
||Highlight $
−
||Let's  delete '''$''' signs in the program.
+
||Let's  delete '''$''' sign in the program.
 
|-
 
|-
 
||
 
||
Line 156: Line 173:
 
'''you cannot put “=” here'''
 
'''you cannot put “=” here'''
 
|-
 
|-
−
||Replace '''$''' signs
+
||Highlight Line number 2
−
||Let's replace the '''$''' signs and run again.
+
||Error is in line number 2.
 +
|-
 +
||Show error
 +
||This syntax error  occured, as there is no container  of variables.
 +
|-
 +
||Replace $ signs  
 +
||Let's replace the $ sign and run again.  
  
 
Program runs properly  
 
Program runs properly  
Line 169: Line 192:
  
 
'''text string was not properly closed, expected a double quote “ ” to close the string.'''
 
'''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  
 
||Replace the quotes  
−
||Let's replace the quotes and run again.
+
||So I will  go to line number 5 and replace the quotes.
 +
 
 +
press F5 key to run the program.
 +
 
 +
Program runs without errors.  
  
−
press '''F5''' key run the program.
+
This way you can find the line at which error has occured, and correct it.
  
−
program runs without errors.
 
 
|-
 
|-
 
||
 
||
Line 194: Line 223:
 
* Trying to multiply or divide by a variable that contains no value.
 
* Trying to multiply or divide by a variable that contains no value.
  
−
*  Run a loop without a condition or increment.
+
*  Run a loop without a condition or increment value.
−
|-
+
−
||
+
−
||Next we will look at errors related to '''print''' command
+
 
|-
 
|-
 
||
 
||
 
||I already have a program in a text editor.  
 
||I already have a program in a text editor.  
 
|-
 
|-
−
||'''reset'''
+
||reset
 +
$a=ask "enter a number for 'a' and click Ok"
 +
$r = ask "enter a number for 'r' and click OK"
 +
$d=$a/$r
  
−
'''$C= ask "enter any number in celsius scale and click OK"'''
+
print $d
 +
||
 +
Let me copy the program into Kturtle Editor
 +
Please pause the tutorial and type the program into your KTurtle editor
  
−
'''message "$F is Fahrenheit"'''
+
Resume the tutorial after typing the program.  
−
 
+
−
'''$F=(9/5*$C)+32'''
+
−
 
+
−
'''go 40,40'''
+
−
 
+
−
'''print "Value in Fahrenheit =" +" "+ $F+"F"'''
+
−
||Let me copy the program into Kturtle Editor
+
−
 
+
−
Please pause the tutorial and type the program into '''KTurtle''' editor
+
−
 
+
−
 
+
−
Resume the tutorial after typing the program.
+
 
|-
 
|-
 
||Zoom text
 
||Zoom text
Line 224: Line 244:
 
It may possibly be a little blurred.
 
It may possibly be a little blurred.
 
|-
 
|-
−
||Highlight '''"Value in Kelvin ="+ $K + "K"'''  and delete
+
||Run the program  
−
||Let's delete line after the  keyword '''print''' '''"Value in Kelvin ="+ $K + "K"'''
+
Let's click on the Run button to run the program.  
−
|-
+
−
||Run the program
+
−
||Let's click on Run button to run the program.
+
  
−
Complier does not shows any error.
+
Complier does not show any error.  
  
−
Here we get an error as the program runs.
+
Let's enter 5 for 'a' and click OK
 +
enter 0 for 'r' and click OK
  
−
'''The print command was called with 0 but it needs 1 parameter.'''
+
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 occurrec as we cannot divide a number with zero.
 +
|-
  
−
It is a runtime error.
+
||
 +
||Next we will learn about logical errors.
 
|-
 
|-
−
||Replace the deleted line
+
||Logical errors
  
−
||Let's replace the deleted line and Run again
+
||Logical error is a mistake in a program's source code that results in incorrect or unexpected behavior.
  
−
program runs without runtime errors.
+
For example,
−
|-
+
Assigning a value to the wrong variable.
−
||
+
 
−
||Next let's look at run time errors in '''loops.'''
+
Multiplying two numbers instead of adding.
 
|-
 
|-
 
||
 
||
 
||I already have a program in a text editor.  
 
||I already have a program in a text editor.  
 
|-
 
|-
−
||'''#program to find multiples of 2'''
+
||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 }
  
−
'''reset'''
+
Let me copy the program into Kturtle Editor  
−
 
+
Please pause the tutorial and type the program into your KTurtle editor  
−
'''$x=0'''
+
−
 
+
−
'''message"In while loop, code inside the loop repeats till boolean evaluates false"'''
+
−
 
+
−
'''while $x<20 {'''
+
−
 
+
−
'''$x=$x+2'''
+
−
 
+
−
'''$x=$x*1'''
+
−
 
+
−
'''fontsize 15'''
+
−
 
+
−
'''forward 20'''
+
−
 
+
−
'''print $x }'''
+
−
||Let me copy the program into '''Kturtle''' Editor
+
−
 
+
−
Please pause the tutorial and type the program into your '''KTurtle''' editor  
+
−
 
+
−
 
+
−
Resume the tutorial after typing the program.
+
  
 +
Resume the tutorial after typing the program.
 
|-
 
|-
 
||Zoom text
 
||Zoom text
Line 282: Line 297:
 
It may possibly be a little blurred.
 
It may possibly be a little blurred.
 
|-
 
|-
−
||Highlight  '''$x=$x+2''' and '''$x=$x*1'''
+
||Run the program  
−
||Let's delete the lines '''$x=$x+2'''  and ''' $x=$x*1'''
+
−
|-
+
−
||Run the program
+
−
||Let's click on the '''Run''' button to run the program.
+
  
−
Complier does not show any error.
+
Highlight “ while”  loop condition
 +
||Let's click on the Run button to run the program.
 +
Complier does not show any error.  
  
−
We get a runtime error.
+
Loop goes into an infinite loop.  
  
−
Loop become an infinite loop of zeros.  
+
We see that “while” loop prints number from 31 and it is still printing.
−
|-
+
−
||Abort the process
+
−
||I will click on '''Abort'''  button to abort the process.
+
−
|-
+
−
||Undo the deleted line
+
−
||Let's undo the deleted line and '''Run''' again
+
  
−
program runs properly as expected.
+
This is a logical error.
−
|-
+
−
||
+
−
||Let's now try another example for runtime error.
+
−
|-
+
−
||
+
−
||I already have a program in a text editor.
+
−
|-
+
−
||'''reset'''
+
  
−
'''$x=8'''
+
In this “while” condition x is greater than 20,
 +
but the variable x is always greater than 20
  
−
'''$r = 1'''
+
So the loop never terminates.
  
−
'''for $i = 1 to $x {'''
 
−
 
−
'''$r = $r * $i'''
 
−
 
−
'''forward 20'''
 
−
 
−
'''print $r }'''
 
−
||Let copy the program into '''KTurtle''' Editor.
 
−
 
−
Please pause the tutorial and type the program into '''KTurtle''' editor
 
−
 
−
 
−
Resume the tutorial after typing the program.
 
 
|-
 
|-
−
||Zoom text
+
||Abort the process
−
||Let me zoom into the program text.
+
||I will click on Abort button to abort the process.  
−
It may possibly be a little blurred.
+
 
|-
 
|-
−
||Highlight  '''$r = $r * $i'''  and  print $r
+
||Change $x=$x+1 to $x=$x-1
−
||Let's delete the lines  ''' $r = $r * $i'''  and  '''print $r'''
+
||Let's Change $x=$x+1 to $x=$x-1.
 +
Run again.
 +
program runs properly.
 +
Loop terminates after printing values from 29 to 20.
 
|-
 
|-
−
||Run the program
 
−
||Let's click on the Run button to run the program.
 
−
 
−
Complier does not show any error.
 
−
 
−
We get a runtime error.
 
−
 
−
We see that only the Turtle has moved forward.
 
−
 
−
'''“for”''' loop is not executed.
 
−
|-
 
−
||Undo the deleted line
 
−
||Let's undo the deleted lines and Run again.
 
−
 
−
Program runs properly as expected.
 
−
|-
 
−
||
 
 
||With this we come to the end of this tutorial.
 
||With this we come to the end of this tutorial.
 
let us summarise.
 
let us summarise.
Line 366: Line 338:
  
 
* Runtime errors
 
* Runtime errors
 +
 +
* Logical errors
 
|-
 
|-
 
||Slide Number 10
 
||Slide Number 10

Revision as of 18:05, 16 January 2013

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

Let 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.

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 any angle value and click OK"

$radian=(pi/180)*$degree

go 50,50

print "Value in radians is"+ " " +$radian

spritehide

Let me 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 inbuilt 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 $ signs 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 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 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

Let me copy the program into Kturtle Editor Please 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

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 occurrec 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 }

Let me copy the program into Kturtle Editor Please 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

Let's 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 number 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 come to the end of this tutorial.

let us summarise.

Slide Number 9

Summary

In this tutorial we have learnt, 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

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