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

Welcome to this tutorial on Common Errors in KTurtle.

Learning Objectives

• Syntax errors

• Runtime errors

• Logical errors

System Requirement

Ubuntu Linux OS v. 12.04.

KTurtle v. 0.8.1 beta.

Pre-requisites

If not,

for relevant tutorials, please visit our website.

http://spoken-tutorial.org

Definition of Error

Error is a mistake in a program that produces an incorrect or unexpected result.

Syntax Errors

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.

Dash home >>Search bar appears>> In the Search bar type KTurtle Click on the KTurtle icon.

Click on Dash home. The Search bar appears.

In the Search bar, type KTurtle.

Click on the KTurtle icon.

$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

Pause the tutorial and type the program your into KTurtle editor

Resume the tutorial after typing the program.

It may possibly be a little blurred.

$a=ask "enter any number and click Ok"

Complier shows the following error,

The variable "$a" was used without first being assigned to a value.

Remove the comment

press F5 key to run the program

We see that the program runs without errors.

$degree=ask "enter an angle value and click OK"

$radian=(pi/180)*$degree

go 50,50

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

spritehide

Pause the tutorial and type the program your into KTurtle editor

Resume the tutorial after typing the program.

It may possibly be a little blurred.

Complier shows the following error,

you cannot put “=” here

Program runs properly

Complier shows the following error,

text string was not properly closed, expected a double quote “ ” to close the string.

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.

Runtime errors

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.

$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.

It may possibly be a little blurred.

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”

For example,

Assigning a value to the wrong variable.

Multiplying two numbers instead of adding.

$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 }

Pause the tutorial and type the program into your KTurtle editor

Resume the tutorial after typing the program.

It may possibly be a little blurred.

Highlight “ while” loop condition

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.

Run again.

program runs properly.

Loop terminates after printing values from 29 to 20.

Let us summarise.

Summary

• Use of variable that has not been declared.

• Missing quotes in strings.

• Errors related to print command

• Runtime errors

• Logical errors

Assignment

$x=3

$y=3

if $x==$y

print"they are equal"

else {

print "they are not equal"}

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 ="+

learn sum $x {

{$r=0

for $i= 1 to $x{

return $r}

}

print

Acknowledgement

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

Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to contact@spoken-tutorial.org

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