Difference between revisions of "Ruby/C2/Control-Statements/English-timed"

| Welcome to the spoken tutorial on Control Statements in ''' Ruby.'''  

| In this tutorial we will learn to use

| ''' if statement '''

 

|''' elsif statement '''

| ''' else'''

 

|''' case statements'''

|Here we are using  

 

|  00:15

|  ''' Ubuntu''' version 12.04  

|''' Ruby '''1.9.3  

|To follow this tutorial, you must have ''' Internet''' Connection.   

| You must also have knowledge of '''Linux''' commands, ''' Terminal''' and ''' Text-editor.'''

 

 

|  Before we begin, recall that we had created ''' “ttt” ''' directory earlier.  

|Then to ''' ruby hyphen tutorial'''   ''' control hyphen statements'''  

| The syntax of the ''' if statement''' in '''Ruby''' is as follows:  

|''' if “condition” '''

|  ''' ruby code'''  

 

|'''end'''  

|Create a new file in ''' gedit''' as shown in the basic level '''Ruby''' tutorials.   

|Name it ''' if hyphen statement dot rb'''

|I have a working example of the ''' if statement.'''  

 

|  You can pause the tutorial, and type the code as we go through it.  

|I have declared an ''' if statement''' in this example.  

| Then I declare an ''' if''' statement.  

|The '''if statement''' will check the value of ''' my_num''' is greater than 0.  

|Now, let us switch to the '''terminal''' and type  

|  ''' ruby space if hyphen statement dot rb'''  

|You should now be able to write your own ''' if statement''' in '''Ruby.'''

| Let's look at the ''' if-else statement''' next.  

|''' if “condition” '''

 

| ''' ruby code'''  

|'''else'''

 

| 02:21

| '''ruby code '''

|Create a new file in ''' gedit''' as shown in the basic level ''' Ruby''' tutorials.   

 

|Name it ''' if hyphen else hyphen statement dot rb'''

|I have a working example of the ''' if-else statement.'''  

|  You can pause the tutorial, and type the code as we go through it.  

|I have declared an ''' if-else statement''' in this example.  

|The '''if''' statement will check if the value of ''' my_num''' is greater than 0.  

 

|  Now, let us switch to the '''terminal''' and type  

|  and see the output.

 

|The output will display ''' “The value of my_num is lesser than 0”.'''  

| You should now be able to write your own ''' if-else statement''' in '''Ruby.'''

|'''end '''

 

|Let us look at an example.  

| Create a new file in '''gedit''' as shown in the basic level '''Ruby''' tutorials.  

 

|Name it ''' if hyphen elsif hyphen statement dot rb'''

 

| I have a working example of the ''' if-elsif- statement.'''  

 

|You can pause the tutorial, and type the code as we go through it.  

|Here also, I have declare a local variable '''my_num''' and assign the value -1 to it.  

| If it is, it will print out the specified string.  

 

| If this is not ''' true''' , it will go into the '''elsif''' section.  

|If it is true, it will print out the string that is specified there.  

| The value of '''my_num''' is neither greater than 0 nor equal to -1 it will go into the '''else''' section.  

 

|But since the value of '''my_num = -1''' it will not proceed to the else block.  

|And it will exit the ''' conditional statement.'''  

|Now, let us switch to the ''' terminal''' and type  

|Let's save the code and execute it on the terminal.  

|So, now it fulfills the if condition and the specified string is printed.  

| The value of ''' my_num''' is greater than 0

|Let's go back to our file and change the value of  ''' my_num''' to -5

|Lets save the code and execute it on the terminal

|  In this case it fulfills the ''' else''' condition and the puts statement within the else block gets executed.  

|You should now be able to write your own ''' if- elsif''' statement in ''' Ruby. '''

|Let us look at the ''' case statement''' next.  

| The ''' case statement''' is a ''' control flow statement''' based on a particular selection.  

| Let us look at the syntax of the '''case statement''' in order to understand this statement.  

|''' case variable'''

|''' when “value 1” '''

|'''ruby code '''

 

|''' when “value 2” '''

 

| '''ruby code '''

| '''else'''

 

| ''' ruby code '''

 

 

|'''end'''

|Create a new file in ''' gedit''' as shown in the basic level '''Ruby''' tutorials.  

|Name it '''case hyphen statement dot rb'''

|I have a working example of the ''' case statement.'''

|You can pause the tutorial, and type the code as we go through it.  

|I have declared an ''' case statement''' in this example.  

|Here I have a '''print statement,''' which will print a question on the terminal.  

|Then I call a '''gets''', which will accept a single line of data from the standard input.  

|Then I declare a case statement.  

|Within that I declare a '''when statement '''.  

 

|This checks whether the specified string matches value of ''' domain.'''  

|First it checks whether the value of '''domain''' is ''' “UP”. '''

|If it is so, it will print out ''' “Uttar Pradesh” ''' and exit the '''case statement.'''  

|At this point it will encounter the ''' else statement'''  

|as none of the above conditions were true.  

|It will subsequently execute the ''' ruby code''' that follows the '''else''' declaration.  

|Now, save the file, switch to the ''' terminal''' and type  

 

|Next execute the ''' Ruby''' file again, like before.  

 

|This time at the prompt type ''' “KL”''' and see the output.  

|Next execute the file one more time.  

|This time at the prompt type in ''' “TN”''' and see the output.  

|You should now be able to write your own ''' case-statements''' in '''Ruby. '''

|Let's summarize.  

 

|In this tutorial we have learnt to use  

 

|''' if statement'''  

|''' else''' construct  

 

|'''if-elsif''' and  

|''' case statements'''  

|As an assignment :

 

|-

|Write a '''Ruby''' program :

 

|that prompts a user to enter a number  

 

|to check if the number is a multiple of 2  

|if it is, then print “The number entered is a multiple of 2”  

|if not, it should check if it is a multiple of 3  

|if it is, then print “The number entered is a multiple of 3”  

|if not, it should check if it a multiple of 4  

|if it is, then print “The number entered is a multiple of 4”  

|if not, it should print “The number is not a multple of 2, 3 or 4”  

|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 spoken hyphen tutorial dot org slash NMEICT hyphen Intro

|This is Anjani Nair signing off. Thanks for watching.