Difference between revisions of "Ruby/C2/Ruby-Methods/English-timed"

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{| border=1

|| '''Narration'''

|| '''Narration'''

|-

|-

| Welcome to the Spoken Tutorial on '''Ruby Methods'''.

| Welcome to the Spoken Tutorial on '''Ruby Methods'''.

|-

|-

|  In this tutorial we will learn

|  In this tutorial we will learn

|-

|-

| What is a '''method''' ?

| What is a '''method''' ?

|-

|-

| Syntax for '''method''' and

| Syntax for '''method''' and

|-

|-

| We will Some examples

| We will Some examples

|-

|-

|  Here we are using ''Ubuntu Linux '''version 12.04  '''Ruby''' 1.9.3

|  Here we are using ''Ubuntu Linux '''version 12.04  '''Ruby''' 1.9.3

|-

|-

| To follow this tutorial you must have knowledge of using '''Terminal '''and '''Text editor '''in '''Linux'''.  

| To follow this tutorial you must have knowledge of using '''Terminal '''and '''Text editor '''in '''Linux'''.  

|-

|-

|  Let us now start with an introduction to '''methods.'''

|  Let us now start with an introduction to '''methods.'''

|-

|-

|A '''Method''' is a self-contained program executing a specific task.  

|A '''Method''' is a self-contained program executing a specific task.  

|-

|-

|'''Ruby method''' is very similar to functions in any other programming language.

|'''Ruby method''' is very similar to functions in any other programming language.

|-

|-

| '''Method''' name should begin with a lowercase letter.

| '''Method''' name should begin with a lowercase letter.

|-

|-

|'''Methods''' should be defined before calling them.

|'''Methods''' should be defined before calling them.

|-

|-

|  Let us see the syntax for '''Method'''

|  Let us see the syntax for '''Method'''

|-

|-

|'''Methods '''are defined using the keyword '''def''' followed by the '''method''' name.

|'''Methods '''are defined using the keyword '''def''' followed by the '''method''' name.

|-

|-

|The '''arguments''' specify values that are passed to the '''method''', to be processed.  

|The '''arguments''' specify values that are passed to the '''method''', to be processed.  

|-

|-

| '''ruby code''' section represents the body of the  '''method''' that performs the processing.'' ''

| '''ruby code''' section represents the body of the  '''method''' that performs the processing.'' ''

|-

|-

|The '''method''' body is enclosed by this definition on the top and the word '''end''' on the bottom

|The '''method''' body is enclosed by this definition on the top and the word '''end''' on the bottom

|-

|-

|This is called as method with arguments.

|This is called as method with arguments.

|-

|-

|  Another syntax for method is

|  Another syntax for method is

|-

|-

|The keyword '''def '''followed by the '''method name''' and an empty argument list

|The keyword '''def '''followed by the '''method name''' and an empty argument list

|-

|-

| '''ruby code''' section  that represents the body of the  '''method''' .'' ''

| '''ruby code''' section  that represents the body of the  '''method''' .'' ''

|-

|-

|And the word end  that marks end of method

|And the word end  that marks end of method

|-

|-

|This is called as method without arguments.

|This is called as method without arguments.

|-

|-

|  Let's see how to use a method.

|  Let's see how to use a method.

|-

|-

|I have already typed a program in the '''gedit''' editor.  

|I have already typed a program in the '''gedit''' editor.  

|-

|-

|Let me open it.

|Let me open it.

|-

|-

|  Please note that our filename is '''method hyphen without hyphen argument dot rb'''

|  Please note that our filename is '''method hyphen without hyphen argument dot rb'''

|-

|-

|I have saved the file inside the  '''rubyprogram''' folder.

|I have saved the file inside the  '''rubyprogram''' folder.

|-

|-

|  In this program we will calculate the sum of two numbers using '''method'''.

|  In this program we will calculate the sum of two numbers using '''method'''.

|-

|-

| Let us go through the program.

| Let us go through the program.

|-

|-

| Here we have declared a global variable '''a.'''

| Here we have declared a global variable '''a.'''

|-

|-

|And we have initialized it by assigning value of '''5'''.  

|And we have initialized it by assigning value of '''5'''.  

|-

|-

|Global variable names are prefixed with a''' dollar sign ($)'''.

|Global variable names are prefixed with a''' dollar sign ($)'''.

|-

|-

|  Global variables are accessible from anywhere in the '''Ruby''' program; regardless of where they are declared.

|  Global variables are accessible from anywhere in the '''Ruby''' program; regardless of where they are declared.

|-

|-

| Here we have declared a method called '''add''' without any arguments.

| Here we have declared a method called '''add''' without any arguments.

|-

|-

|  Here we ask the user to enter the second number.

|  Here we ask the user to enter the second number.

|-

|-

|  User will enter the value.  

|  User will enter the value.  

|-

|-

| '''gets method''' gets  the  input from the console but in a  '''string '''format.

| '''gets method''' gets  the  input from the console but in a  '''string '''format.

|-

|-

| So we need to convert it into '''integer''', using '''to_i '''method.

| So we need to convert it into '''integer''', using '''to_i '''method.

|-

|-

|  The converted value is  then stored in the variable '''b .''' '''b '''is a local variable.

|  The converted value is  then stored in the variable '''b .''' '''b '''is a local variable.

|-

|-

|It is available only to the '''method''' inside which it is declared.

|It is available only to the '''method''' inside which it is declared.

|-

|-

| Here we add the values of global variable '''a '''and variable '''b.'''

| Here we add the values of global variable '''a '''and variable '''b.'''

|-

|-

|The result is  then stored in variable '''sum.'''

|The result is  then stored in variable '''sum.'''

|-

|-

| Then we print the '''sum.'''

| Then we print the '''sum.'''

|-

|-

|  This shows a way of inserting a variable within a string.

|  This shows a way of inserting a variable within a string.

|-

|-

|Here the content of '''sum''' is returned as a '''string''' and is substituted into the outer '''string'''.

|Here the content of '''sum''' is returned as a '''string''' and is substituted into the outer '''string'''.

|-

|-

|  '''end''' marks the end of the method.

|  '''end''' marks the end of the method.

|-

|-

|  There are two types of methods.

|  There are two types of methods.

|-

|-

|'''User-defined method''' - that is our '''add''' method.

|'''User-defined method''' - that is our '''add''' method.

|-

|-

|'''Pre-defined method '''- that is '''print''', '''gets''' and '''to_i''' method.

|'''Pre-defined method '''- that is '''print''', '''gets''' and '''to_i''' method.

|-

|-

|  Here we call our '''add '''method.

|  Here we call our '''add '''method.

|-

|-

|The addition operation will be performed and the result will be  printed.  

|The addition operation will be performed and the result will be  printed.  

|-

|-

|  Now let us click on the  '''Save. ''' button.

|  Now let us click on the  '''Save. ''' button.

|-

|-

|This program will be saved in''' rubyprogram''' folder as mentioned earlier.

|This program will be saved in''' rubyprogram''' folder as mentioned earlier.

|-

|-

|Now let us execute the program.

|Now let us execute the program.

|-

|-

|  Open the terminal by pressing the '''Ctrl, Alt and T '''keys simultaneously.  

|  Open the terminal by pressing the '''Ctrl, Alt and T '''keys simultaneously.  

|-

|-

|A terminal window appears on  your screen.

|A terminal window appears on  your screen.

|-

|-

|  To execute the program, we need to go to the subdirectory '''rubyprogram'''.

|  To execute the program, we need to go to the subdirectory '''rubyprogram'''.

|-

|-

|  So let's type '''cd'' '''''space'' '''''Desktop/rubyprogram'' '''''and press '''Enter.'''

|  So let's type '''cd'' '''''space'' '''''Desktop/rubyprogram'' '''''and press '''Enter.'''

|-

|-

|  Now Type '''ruby '''space '''method hyphen without hyphen argument dot rb''' and press '''Enter'''

|  Now Type '''ruby '''space '''method hyphen without hyphen argument dot rb''' and press '''Enter'''

|-

|-

|  '''Enter the second number '''is displayed.

|  '''Enter the second number '''is displayed.

|-

|-

|I will enter value as '''4.''' type 4 and press enter

|I will enter value as '''4.''' type 4 and press enter

|-

|-

|  We get the output as -  '''Sum of two numbers 5 and 4 is 9'''

|  We get the output as -  '''Sum of two numbers 5 and 4 is 9'''

|-

|-

|  Now let us see an example of '''method''' with arguments.  

|  Now let us see an example of '''method''' with arguments.  

|-

|-

|I have already typed this program in the '''gedit''' editor,  let me open it.

|I have already typed this program in the '''gedit''' editor,  let me open it.

|-

|-

|  Please note that our filename is '''method hyphen with hyphen argument dot rb'''

|  Please note that our filename is '''method hyphen with hyphen argument dot rb'''

|-

|-

|I have saved this file also inside the '''rubyprogram''' folder.

|I have saved this file also inside the '''rubyprogram''' folder.

|-

|-

|  Let us go through the program.

|  Let us go through the program.

|-

|-

|  Here we have declared a '''method''' called '''add.'''  '''a,b''' are the arguments of the '''method add. '''

|  Here we have declared a '''method''' called '''add.'''  '''a,b''' are the arguments of the '''method add. '''

|-

|-

|  Here the values of '''a''' and '''b''' are added.

|  Here the values of '''a''' and '''b''' are added.

|-

|-

|And the sum is returned to the '''method '''call.

|And the sum is returned to the '''method '''call.

|-

|-

|  '''end''' marks the end of method.

|  '''end''' marks the end of method.

|-

|-

|  Here we are asking the user for input.  

|  Here we are asking the user for input.  

|-

|-

|User will enter the values of a and b.  

|User will enter the values of a and b.  

|-

|-

|The values will be stored in variable '''a''' and  '''b, '''respectively.

|The values will be stored in variable '''a''' and  '''b, '''respectively.

|-

|-

|  Here we call the  '''add''' '''method'''

|  Here we call the  '''add''' '''method'''

|-

|-

|Then we pass the arguments as '''a''' and '''b.'''

|Then we pass the arguments as '''a''' and '''b.'''

|-

|-

|  The value returned by the '''method add''' ,''' '''after performing the addition operation will be stored in '''c.'''

|  The value returned by the '''method add''' ,''' '''after performing the addition operation will be stored in '''c.'''

|-

|-

|  Here we print the sum which is store in '''c'''.

|  Here we print the sum which is store in '''c'''.

|-

|-

| Lets execute this code. Go to the terminal.

| Lets execute this code. Go to the terminal.

|-

|-

|Let us first clear the terminal.  Type''' clear''' and press enter

|Let us first clear the terminal.  Type''' clear''' and press enter

|-

|-

| We are already in the subdirectory '''rubyprogram.'''

| We are already in the subdirectory '''rubyprogram.'''

|-

|-

|  Now, press the up arrow key twice to get the previous command.

|  Now, press the up arrow key twice to get the previous command.

|-

|-

|Replace '''method hyphen without hyphen arguments dot rb''' with '''method hyphen with hyphen arguments dot rb '''

|Replace '''method hyphen without hyphen arguments dot rb''' with '''method hyphen with hyphen arguments dot rb '''

|-

|-

| And Press''' Enter'''

| And Press''' Enter'''

|-

|-

|  '''Enter the values of a and b '''is displayed.

|  '''Enter the values of a and b '''is displayed.

|-

|-

|I will enter''' 8 '''and''' 9.'''

|I will enter''' 8 '''and''' 9.'''

|-

|-

|Type 8 and press Enter

|Type 8 and press Enter

|-

|-

|Type 9 and press Enter

|Type 9 and press Enter

|-

|-

| We get the output as

| We get the output as

|-

|-

|'''Sum of two numbers 8 and 9 is 17.'''

|'''Sum of two numbers 8 and 9 is 17.'''

|-

|-

|Now I will show you one important feature of '''Ruby''' '''method.'''

|Now I will show you one important feature of '''Ruby''' '''method.'''

|-

|-

| Let's go back to the program in the text editor.

| Let's go back to the program in the text editor.

|-

|-

|Delete the keyword '''return.'''

|Delete the keyword '''return.'''

|-

|-

|Now click on '''Save''' button.

|Now click on '''Save''' button.

|-

|-

| Let's execute the code.Go to the terminal.

| Let's execute the code.Go to the terminal.

|-

|-

| Press the up arrow key to get the previous command and  Press''' Enter.'''

| Press the up arrow key to get the previous command and  Press''' Enter.'''

|-

|-

|''Enter the values of a and b '''is displayed.  

|''Enter the values of a and b '''is displayed.  

|-

|-

|I will enter''' 10 '''and''' 15.'''

|I will enter''' 10 '''and''' 15.'''

|-

|-

|Type 10,  press Enter Type 15 and press Enter

|Type 10,  press Enter Type 15 and press Enter

|-

|-

|  We get the output as

|  We get the output as

|-

|-

|'''Sum of two numbers 10 and 15 is 25. '''

|'''Sum of two numbers 10 and 15 is 25. '''

|-

|-

|  We can see that the program is executed without any error, even after deleting the keyword '''return.'''

|  We can see that the program is executed without any error, even after deleting the keyword '''return.'''

|-

|-

|  This is because '''Ruby '''automatically returns the value calculated in the '''method.'''

|  This is because '''Ruby '''automatically returns the value calculated in the '''method.'''

|-

|-

|The keyword '''return''' in '''method''' is optional in '''Ruby.'''

|The keyword '''return''' in '''method''' is optional in '''Ruby.'''

|-

|-

|  This brings us to the end of this Spoken Tutorial.

|  This brings us to the end of this Spoken Tutorial.

|-

|-

| Let us switch back to slides

| Let us switch back to slides

|-

|-

|Let us summarize

|Let us summarize

|-

|-

|In this tutorial we have learnt

|In this tutorial we have learnt

|-

|-

|About '''Methods'''

|About '''Methods'''

|-

|-

| Syntax  for '''Method''' without arguments

| Syntax  for '''Method''' without arguments

|-

|-

|And  '''Method''' with arguments

|And  '''Method''' with arguments

|-

|-

| Returning value from '''method'''  

| Returning value from '''method'''  

|-

|-

|  As an assignment

|  As an assignment

|-

|-

|Write a program,to calculate area of a square  

|Write a program,to calculate area of a square  

   

   

|-

|-

| by using '''method '''and

| by using '''method '''and

|-

|-

| by getting the input from user  

| by getting the input from user  

|-

|-

|  Watch the video available at the following link.

|  Watch the video available at the following link.

|-

|-

|It summarises the Spoken Tutorial project.

|It summarises the Spoken Tutorial project.

|-

|-

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

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

|-

|-

|  The Spoken Tutorial Project Team :

|  The Spoken Tutorial Project Team :

|-   

|-   

|Conducts workshops using spoken tutorials  

|Conducts workshops using spoken tutorials  

|-

|-

|Gives certificates to those who pass an online test  

|Gives certificates to those who pass an online test  

|-

|-

|For more details, please write to contact@spoken-tutorial.org

|For more details, please write to contact@spoken-tutorial.org

|-

|-

|  Spoken Tutorial Project is a part of the Talk to a Teacher project.

|  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.

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

|-

|-

|More information on this Mission is available at the below link

|More information on this Mission is available at the below link

|-

|-

|This is Afrin Pinjari from IIT Bombay, signing off.

|This is Afrin Pinjari from IIT Bombay, signing off.

|-

|-

|Thank you for watching.

|Thank you for watching.

|}

|}