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

|'''Narration'''

||In this tutorial, we will learn about:

||* '''Syntax errors'''   

||* '''Run time errors'''  and

||* '''Logical errors'''.

||To record this tutorial, I am using:

|* '''Ubuntu Linux OS''' version '''12.04'''  

|* '''KTurtle''' version '''0.8.1 beta'''.

||We assume that you have basic working knowledge of '''KTurtle'''.  

|If not,  for relevant tutorials, please visit our website:

http://spoken-tutorial.org'''

||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.'''

|| '''Syntax error''' is a violation of  grammatical rules of a programming language.

||* Unmatched parentheses, square and curly braces.  

||* Use of ''' variable''' that has not been declared.

||* Missing '''quotes''' in '''strings.'''

||Let's open a new '''KTurtle''' '''Application'''.

|Click on  '''Dash  home'''. In the '''Search bar''', type: "KTurtle".

||I already have a program in a '''text editor'''.  

||To explain the '''error''' in the program, I will '''comment''' part of the '''code'''.  

||Here, I will '''comment''' the line.

||'''$a=ask''' within double quotes '''"enter any number and click Ok"'''.

||I will use hash(#) sign to comment the line.

||I will copy the program from '''text editor''' and paste it into '''Kturtle's''' Editor.

|Pause the tutorial here and type the program into  your '''KTurtle''' editor.

||Let's click on '''Run''' button to '''run''' the program.

|Compiler shows the following error:

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

||Here, the error is in line number 4.

||This is a '''syntax error'''. It occurred as the variable  'a' was not declared.

||So, I will go to line number 2, remove the comment.

||Let's click on '''Run''' button to '''run''' the program.

|Enter '6' for 'a' value and click '''OK'''.

|| Let's next look at another error.

||Here the value of "'''pi'''" is predefined in KTurtle.

||Let's delete the '$' sign in the program.  

||I will copy the program from text editor and paste it into ''' Kturtle's Editor'''.

|Pause the tutorial here and type the program into your  '''KTurtle editor'''  

||Let's Click on '''Run''' button to '''run''' the program.  

|Complier shows the following error:

|'''"You cannot put '=' here"'''.

||This is a syntax error. It occurred as there is no '''container''' of variable.

||Let's go back to the program, replace the '$' sign.

||I will copy the program from text editor and paste it into '''KTurtle's''' Editor.

||Let's click on '''Run''' button to '''run''' the program.

|Enter 45 for angle value and click '''OK'''.

||Let's remove one of the quotes of the '''string'''.  

|| I will copy the program from text editor and paste it into '''KTurtle's ''' Editor.

||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'.'''

||I will copy the program from text editor and paste it into''' Kturtle's''' Editor.

||Click on '''Run''' button to run the program.

||Enter '45' for angle value and click '''OK'''.

|This way you can find the line at which error has occurred and also correct it.  

||Let's now learn about '''run time''' errors.

|'''Runtime errors''' are commonly due to wrong '''input''' from the user.  

|Compiler cannot find these '''errors'''.

|* Trying to divide by a '''variable''' that contains no value.

|* Run a loop without a terminating '''condition''' or '''increment value'''.

|This program divides two numbers.

|Pause the tutorial and type the program into your '''KTurtle''' editor.

|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'''”.

||This error occurs as we cannot divide a number with zero.

||Let us '''run''' again.  

|Enter '5' for 'a' and click '''OK''',

|enter '2' for 'r' and click '''OK'''.

||Next, we will learn about ''' 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 will copy the program from text editor and paste it into '''Kturtle's''' Editor.

|Pause the tutorial here and type the program into your '''KTurtle''' editor.

||A dialog box pops-up; let's click '''OK'''.

||We see that '''“while”''' loop prints numbers from 31 and is still printing.

||In the “while” condition 'x' is greater than 20

||but the '''variable 'x'''' is always greater than 20.

||So, the loop never terminates.

||A dialog box pop-up. Let us click '''OK'''.

||Loop terminates after printing the values from 29 to 20.  

||With this, we come to the end of this tutorial.

||Let us summarize.

||In this tutorial, we have learnt errors and types of errors such as-

|* Use of variable that has not been declared.

|* Missing '''quotes''' in '''string'''s.

|* '''Runtime errors''' and

||* '''Logical errors'''.

||As an assignment, I would like you to find errors in the given programs.

||Watch the video available at this URl:

http://spoken-tutorial.org/What_is_a_Spoken-Tutorial  

|It summarizes the Spoken Tutorial project.

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

||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

||'''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.