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

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

|  In this tutorial we will learn

| We will Some examples

|  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'''.  

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

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

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

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

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

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

| '''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

|This is called as method with arguments.

|  Another syntax for method is

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

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

|And the word end that marks end of method

|  Let's see how to use a method.

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

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

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

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

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

|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.

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

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

| '''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.

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

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

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

|  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'''.

|   03:25

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

|   There are two types of methods.

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

|  Here we call our '''add '''method.

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

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

|Now let us execute the program.

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

|A terminal window appears on your screen.

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

|  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'''

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

|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'''

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

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

|  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.

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

|  Here we are asking the user for input.  

|User will enter the values of a and b.  

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

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

|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.'''

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

| Lets execute this code. Go to the terminal.

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

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

|  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 '''

| And Press''' Enter'''

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

|Type 8 and press Enter

|Type 9 and press Enter

| We get the output as

 

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

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

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

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

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

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

|Type 10, press Enter Type 15 and press Enter

|'''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.'''

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

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

| Let us switch back to slides

|Let us summarize

|In this tutorial we have learnt

|About '''Methods'''

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

|And '''Method''' with arguments

| Returning value from '''method'''  

|  As an assignment

|Write a program,to calculate area of a square  

| by using '''method '''and

 

| by getting the input from user  

|It summarises the Spoken Tutorial project.

|  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.

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

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