Difference between revisions of "Ruby/C2/Ruby-Methods/English"
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* What is a '''method''' ? | * What is a '''method''' ? | ||
* Syntax for '''method''' and | * Syntax for '''method''' and | ||
| − | * Some examples | + | * We will see Some examples |
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| Line 62: | Line 62: | ||
Syntax for Method | Syntax for Method | ||
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us see the syntax | + | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Let us see the syntax for '''Method''' |
'''def method_name(arguments)''' | '''def method_name(arguments)''' | ||
| Line 102: | Line 102: | ||
| − | The '''ruby code''' section represents the body of the | + | The '''ruby code''' section that represents the body of the |
'''method''' .'' '' | '''method''' .'' '' | ||
| − | + | And the word end thatmarks end of method | |
This is called as method without arguments. | This is called as method without arguments. | ||
| Line 122: | Line 122: | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Please note that our filename is '''method-without-argument.rb''' | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Please note that our filename is '''method-without-argument.rb''' | ||
| − | I have saved the file inside | + | I have saved the file inside the '''rubyprogram''' folder. |
|- | |- | ||
| Line 148: | Line 148: | ||
|- | |- | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''def add()''' | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''def add()''' | ||
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here we have declared a method '''add''' without any arguments. | + | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here we have declared a method called '''add''' without any arguments. |
|- | |- | ||
| Line 160: | Line 160: | ||
|- | |- | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''gets''' | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''gets''' | ||
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''gets method''' gets | + | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| '''gets method''' gets the input from the console but in a '''string '''format. |
|- | |- | ||
| Line 168: | Line 168: | ||
|- | |- | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''b''' | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''b''' | ||
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The converted value is stored in the variable '''b .''' | + | | style= "border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| The converted value is then stored in the variable '''b .''' |
'''b '''is a local variable. | '''b '''is a local variable. | ||
| Line 178: | Line 178: | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here we add the values of global variable '''a '''and variable '''b.''' | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here we add the values of global variable '''a '''and variable '''b.''' | ||
| − | The result is stored in variable '''sum.''' | + | The result is then stored in variable '''sum.''' |
|- | |- | ||
| Line 226: | Line 226: | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Open the terminal by pressing the '''Ctrl, Alt and T '''keys simultaneously. | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Open the terminal by pressing the '''Ctrl, Alt and T '''keys simultaneously. | ||
| − | A terminal window appears on | + | A terminal window appears on your screen. |
|- | |- | ||
| Line 237: | Line 237: | ||
|- | |- | ||
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Type''' ruby method-without-argument.rb'''<nowiki> <<Press </nowiki>'''Enter''' | + | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"|Now Type''' ruby method-without-argument.rb'''<nowiki> <<Press </nowiki>'''Enter''' |
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Type '''ruby '''space '''method-without-argument.rb''' and press '''Enter''' | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Type '''ruby '''space '''method-without-argument.rb''' and press '''Enter''' | ||
| Line 258: | Line 258: | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now let us see an example of '''method''' with arguments. | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Now let us see an example of '''method''' with arguments. | ||
| − | I have already typed this program in the '''gedit''' editor, | + | I have already typed this program in the '''gedit''' editor, let me open it. |
|- | |- | ||
| Line 300: | Line 300: | ||
|- | |- | ||
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''c=add(a,b)''' | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:none;padding:0.097cm;"| Highlight '''c=add(a,b)''' | ||
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here we call the ''' | + | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Here we call the '''add''''''method''' |
Then we pass the arguments as '''a''' and '''b.''' | Then we pass the arguments as '''a''' and '''b.''' | ||
| Line 337: | Line 337: | ||
Replace '''method-without-arguments.rb''' with '''method-with-arguments.rb ''' | Replace '''method-without-arguments.rb''' with '''method-with-arguments.rb ''' | ||
| − | Press''' Enter''' | + | And Press''' Enter''' |
|- | |- | ||
| Line 383: | Line 383: | ||
'''ruby method-with-argument.rb '''<nowiki><< Press</nowiki>''' Enter''' | '''ruby method-with-argument.rb '''<nowiki><< Press</nowiki>''' Enter''' | ||
| − | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Press the up arrow key to get the previous command | + | | style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.097cm;"| Press the up arrow key to get the previous command and |
Press''' Enter.''' | Press''' Enter.''' | ||
| Line 432: | Line 432: | ||
* About '''Methods''' | * About '''Methods''' | ||
| − | * Syntax | + | * Syntax for |
* '''Method''' without arguments | * '''Method''' without arguments | ||
| − | * '''Method''' with arguments | + | * and '''Method''' with arguments |
* Returning value from '''method'''<br/> | * Returning value from '''method'''<br/> | ||
| Line 446: | Line 446: | ||
* to calculate area of a square | * 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 | ||
Revision as of 15:45, 16 April 2013
Title of script: Ruby Methods
Author:Afrin Pinjari
Keywords: method,method syntax, return, video tutorial
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|---|---|
| Slide 1 | Welcome to the Spoken Tutorial on Ruby Methods. |
| Slide 2
Learning Objective |
In this tutorial we will learn
|
| Slide 3
System Requirement |
Here we are using
|
| Slide 4
Pre-requisites |
To follow this tutorial you must have knowledge of using Terminal and Text editor in Linux. |
| Slide 5
What is Methods |
Let us now start with an introduction to methods.
A Method is a self-contained program executing a specific task. Ruby method is very similar to functions in any other programming language. |
| Slide 6
Method |
Method name should begin with a lowercase letter.
Methods should be defined before calling them. |
| Slide 7
Syntax for Method |
Let us see the syntax for Method
def method_name(arguments) ruby code end OR def method_name () ruby code end
method that performs the processing.
This is called as method with arguments. |
| Slide 7 | Another syntax for method is
method . And the word end thatmarks end of method This is called as method without arguments. |
| Switch to the editor – gedit. | Let's see how to use a method.
I have already typed a program in the gedit editor. Let me open it. |
| Point to the filename on the Title bar. | Please note that our filename is method-without-argument.rb
I have saved the file inside the rubyprogram folder. |
| In this program we will calculate the sum of two numbers using method. | |
| Let us go through the program. | |
| Highlight $a=5 | Here we have declared a global variable a.
And we have initialized it by assigning value of 5. Global variable names are prefixed with a dollar sign ($). |
| Global variables are accessible from anywhere in the Ruby program;
regardless of where they are declared. | |
| Highlight def add() | Here we have declared a method called add without any arguments. |
| Highlight print"Enter the second number:" | Here we ask the user to enter the second number. |
| Highlight b=gets.to_i | User will enter the value. |
| Highlight gets | gets method gets the input from the console but in a string format. |
| Highlight to_i | So we need to convert it into integer, using to_i method. |
| Highlight b | 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. |
| Highlight sum=$a+b | Here we add the values of global variable a and variable b.
The result is then stored in variable sum. |
| Highlight puts"Sum of#{ $a} & #{b} is #{sum}" | Then we print the sum. |
| Highlight #{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. |
| Highlight end | end marks end of the method. |
| There are two types of methods.
User-defined method - that is our add method. Pre-defined method - that is print, gets and to_i method. | |
| Highlight add() | Here we call the add method.
The addition operation will be performed and the result will be printed. |
| Click on Save. | Now let us click on Save.
This program will be saved in rubyprogram folder as mentioned earlier. Now let us execute the program. |
| Press Ctrl+Alt+t
Switch to Terminal |
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. | |
| Type cd Desktop/rubyprogram<< Press Enter | So let's type cd space Desktop/rubyprogram and press Enter. |
| Now Type ruby method-without-argument.rb <<Press Enter | Type ruby space method-without-argument.rb and press Enter |
| Enter the second number is displayed.
I will enter value as 4. type 4 and press enter | |
| Highlight Sum of two numbers 5 and 4 is 9 | We get the output as -
Sum of two numbers 5 and 4 is 9 |
| Switch back to editor | Now let us see an example of method with arguments.
I have already typed this program in the gedit editor, let me open it. |
| Point to the filename in the Title bar. | Please note that our filename is method-with-argument.rb
I have saved this file also inside the rubyprogram folder. |
| Let us go through the program. | |
| Highlight def add(a ,b) | Here we have declared a method called add.
a,b are the arguments of the method add. |
| Highlight return a+b | Here the values of a and b are added.
And the sum is returned to the method call. |
| Highlight end | end marks the end of method. |
| Highlight puts"Enter the values of a and b"
a=gets.to_i b=gets.to_i |
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 variable b, respectively. |
| Highlight c=add(a,b) | Here we call the add'method'
Then we pass the arguments as a and b. |
| Highlight c | The value returned by the method add , after performing the addition operation will be stored in c. |
| Highlight puts"Sum of two number #{a} and #{b} is #{c}" | Here we print the sum which is store in c. |
| Switch back to terminal
Type clear<<Press Enter |
Lets execute this code.
Go to the terminal. Let us first clear the terminal Type clear and press enter |
| Point to the command prompt to show subdirectory rubyprogram | We are already in the subdirectory rubyprogram. |
| Replace
ruby method-with-argument.rb << Press Enter |
Now, press the up arrow key twice to get the previous command.
Replace method-without-arguments.rb with method-with-arguments.rb And Press Enter |
| Enter the values of a and b is displayed.
I will enter 8 and 9. Type 8 and press Enter Type 9 and press Enter | |
| Highlight Sum of two numbers 8 and 9 is 17 | We get the output as
Sum of two numbers 8 and 9 is 17. <<pause>> |
| Now I will show you one important feature of Ruby method. | |
| Switch back to the text editor | Let's go back to the program in the text editor. |
| Delete the keyword return. | |
| Click on Save | Now click on Save button. |
| Switch back to terminal | Let's execute the code.
Go to the terminal. |
| Replace
ruby method-with-argument.rb << Press Enter |
Press the up arrow key to get the previous command and
Press Enter. |
| Enter the values of a and b is displayed.
I will enter 10 and 15. Type 10 and press Enter Type 15 and press Enter | |
| Highlight Sum of two numbers 10 and 15 is 25 | We get the output as
Sum of two numbers10 and 15 is 25. |
| We can see that the program is executed without any error, even after deleting the keyword return. | |
| Switch back to the program
Highlight a+b |
This is because Ruby automatically returns the value calculated in the method.
The keyword return in method is optional in Ruby. |
| <<Pause>>
This brings us to the end of this Spoken Tutorial. | |
| Slide 11
Summary |
Let us switch back to slides
Let's summarize In this tutorial we have learnt
|
| Slide 13
Assignment |
As an assignment
Write a program
|
| Slide 14
About the Spoken Tutorial Project |
Watch the video available at the following link.
It summarises the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it. |
| Slide 15 | The Spoken Tutorial Project Team :
Gives certificates to those who pass an online test For more details, please write to |
| Slide 16
|
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: spoken-tutorial.org/NMEICT-Intro. This is Afrin Pinjari from IIT Bombay, signing off. Thank you for watching. |
