Difference between revisions of "PERL/C3/Referencing-and-Dereferencing/Gujarati"

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|'''Reference''' is an easy, compact '''scalar''' value.
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|'''Reference''' એક સરળ સંક્ષિપ્ત સ્કેલર વેલ્યુ હોય છે.
  
 
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|  '''Reference''' will improve the performance of '''Perl''' code when you pass or return large data-structures.
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|  '''Reference''' પર્લ કોડના પ્રદશનને સુધારશે જયારે તમે મોટા ડેટા-સ્ટ્રક્ચર ને પાસ અથવા રીટર્ન કરો છો.
  
 
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|It saves memory as it passes a''' reference''' to a '''subroutine''' rather than passing a value.
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| આ મેમરી સંગ્રહ કરે છે જેમ કે એક વેલ્યુ પાસ પાસ કરવાના બદલે '''subroutine''' પર ''' reference''' પાસ કરે છે.
  
 
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|Easy to manage complicated '''Perl''' data structures.
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| પર્લના જટિલ ડેટા સ્ટ્રક્ચરસ નું સરળતાથી વ્યવસ્થા કરે છે.
  
 
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| Let us learn how to create a '''reference'''.
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| હવે શીખીએ કે '''reference''' ને કેવી રીતે  બનાવાય.
  
 
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| We can create a''' reference''' for any '''variable, subroutine''' or '''value''', by putting a '''backslash (\)''' in front of it.
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|   આપણે આના આગળ એક '''backslash (\)''' લગાડીને કોઈ પણ વેરીએબલ , સબરૂટીન અથવા વેલ્યુના માટે ''' reference''' બનાવી શકીએ છીએ.
  
 
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|A''' scalar variable''' is''' reference'''d by backslash and dollar sign ($) as shown here.
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| એક સ્કેલર વેરીએબલ અહી પ્રદશિત ની જેમ '''backslash (\)''' અને ડોલર ચિન્હ થી રેફરેન્સ કરાવાય છે.
  
 
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|  01:39
 
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|An''' array variable''' is''' reference'''d by backslash and '''at the rate(@)''' symbol.
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| એક ''' array variable''' '''backslash (\)''' અને '''at the rate(@)''' સિમ્બલ રેફરેંસ કરાવાય છે.
  
 
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|  01:45
 
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|A''' hash variable''' is''' reference'''d by backslash and '''percentage(%)''' symbol as shown in the example here.
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| એક ''' hash variable''' અહી ઉદાહરણમાં પ્રદશિતની જેમ '''backslash (\)''' અને '''percentage(%)''' સિમ્બલથી રેફરેંસ કરાવાય છે.
  
 
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| what is '''dereference'''?
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| '''dereference''' શું હોય છે ?
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Revision as of 12:01, 12 February 2016

Time
Narration
00:01 પર્લમાં Referencing and Dereferencing . પરના સ્પોકન ટ્યુટોરીયલમાં તમારું સ્વાગત છે.
00:07 આ ટ્યુટોરીયલમાં આપણે આપણે શીખીશું:
  • Scalar References
  • Array References
  • Hash References
  • Dereferences અને
  • array/hash references ના એલિમેન્ટને કેવી રીતે ઉમેરાઈ, કાઢવાઈ, અને એક્સેસ કરાવાય.
00:22 આ ટ્યુટોરીયલ માટે હું ઉપયોગ કરી રહી છું:
  • Ubuntu Linux 12.04 operating system
  • Perl 5.14.2
  • gedit Text Editor
00:33 તમે તમારી પસંદગી અનુસાર કોઈ પણ ટેક્સ્ટ એડિટર વાપરી શકો છો.
00:37 તમને આપેલની કાર્યકારી જાણકારી હોવી જોઈએ:
  • Perl programming
  • Array functions અને
  • Hash functions.
00:43 જો નથી તો સ્પોકન ટ્યુટોરિયલ વેબ સાઈટ પર ઉપલબ્ધ Perl ટ્યુટોરિયલ જુઓ.
00:49 Reference શું છે?
00:51 એક reference એક variable, array, hash અથવા એક subroutine નું પોઈન્ત્ર એડ્રેસ હોય છે.
00:58 આ સીધું ડેટા નથી ધરાવતું.
01:01 Reference એક સરળ સંક્ષિપ્ત સ્કેલર વેલ્યુ હોય છે.
01:05 Reference પર્લ કોડના પ્રદશનને સુધારશે જયારે તમે મોટા ડેટા-સ્ટ્રક્ચર ને પાસ અથવા રીટર્ન કરો છો.
01:12 આ મેમરી સંગ્રહ કરે છે જેમ કે એક વેલ્યુ પાસ પાસ કરવાના બદલે subroutine પર reference પાસ કરે છે.
01:18 પર્લના જટિલ ડેટા સ્ટ્રક્ચરસ નું સરળતાથી વ્યવસ્થા કરે છે.
01:22 હવે શીખીએ કે reference ને કેવી રીતે બનાવાય.
01:25 આપણે આના આગળ એક backslash (\) લગાડીને કોઈ પણ વેરીએબલ , સબરૂટીન અથવા વેલ્યુના માટે reference બનાવી શકીએ છીએ.
01:33 એક સ્કેલર વેરીએબલ અહી પ્રદશિત ની જેમ backslash (\) અને ડોલર ચિન્હ થી રેફરેન્સ કરાવાય છે.
01:39 એક array variable backslash (\) અને at the rate(@) સિમ્બલ રેફરેંસ કરાવાય છે.
01:45 એક hash variable અહી ઉદાહરણમાં પ્રદશિતની જેમ backslash (\) અને percentage(%) સિમ્બલથી રેફરેંસ કરાવાય છે.
01:53 dereference શું હોય છે ?
01:55 When a reference is dereferenced, the actual value is returned.
02:00 Dereference is done by enclosing the reference variable within curly brackets
02:06 and preceding the left curly bracket with a character denoting the type of reference it is.
02:12 Let us see how to dereference variables.
02:16 A scalar variable is dereferenced by dollar sign ($) and curly brackets.
02:21 An array variable is dereferenced by at the rate (@) symbol and curly brackets.
02:27 A hash variable is dereferenced by percentage(%) symbol and curly brackets.
02:33 Let us see a simple program for Scalar reference and dereference.
02:38 Let me open a sample program in 'gedit' Text editor.
02:43 Open the terminal and type: gedit scalarRef dot pl ampersand and press Enter.
02:50 Type the following code as displayed on the screen.
02:55 Let me explain the code.
02:57 First line declares a scalar variable '$a' and initialized to 10.
03:03 As mentioned earlier, a scalar variable is referenced by backslash and dollar sign ($).
03:10 This line will print memory address of the variable that is created as reference.
03:16 To print the actual value, the variable is dereferenced by curly brackets preceded by '$'.
03:23 Here, ref() function will return the reference type such as scalar or array or hash.
03:30 Now, press Ctrl+S to save the file.
03:34 Let us execute the program.
03:36 Switch to the terminal and type: perl scalarRef dot pl and press Enter.
03:43 The output is displayed as shown.
03:46 First line shows the memory address where the value 10 is stored.
03:51 The second line returns the actual value 10.
03:55 Ref() function returns "SCALAR" as output.
03:59 Next, let us understand how to create a reference and dereference array by using a sample program.
04:07 I already have a sample program. Let me open it in 'gedit' Text editor.
04:13 In the terminal, type: gedit arrayRef dot pl ampersand and press Enter.
04:20 Type the following code as displayed on the screen, in the arrayRef dot pl file.
04:26 Let me explain the code now.
04:28 Here, in the first line, I have declared an array @color and initialized it with three values.
04:35 It is referenced with backslash @color which is the array name and assigned to $colorRef.
04:42 The print statement will print the reference value and the dereferenced value.
04:47 Now, press Ctrl+S to save the file.
04:51 Let us execute the program.
04:53 Switch back to the terminal and type: perl arrayRef dot pl and press Enter.
05:00 The output is displayed as shown here.
05:04 The first line shows the output of the memory address of the variable that is created as reference.
05:10 The second line shows the actual value that is dereferenced.
05:16 Next, we will see how to declare direct reference for an array.
05:21 Let’s come back to our program.
05:24 I have changed the existing program to show the direct reference for an array.
05:29 You can create a direct reference for an array by using square brackets [] as shown.
05:35 Use arrow operator (->) to dereference.
05:39 print statement will print "Green" as output.
05:43 Here, the print statement takes the value of index[1]. i.e 'Green' in our program.
05:50 Press Ctrl+S to save the file.
05:54 Switch back to the terminal and type: perl arrayRef dot pl and press Enter to execute.
06:03 I’ll show an example on how to use the direct hash reference in the same code file.

So, let’s switch to gedit.

06:11 You can create a direct reference to hash by using curly brackets {} as shown here.
06:18 Use arrow operator (->) to dereference it. “Name” is the hash key.
06:24 On executing this block of code, both the print statements will print "Sunil" as output.
06:31 Next we will see how to add, remove, access elements to array reference with a sample program.
06:39 I already have a sample program. Let me open it in gedit text-editor.
06:45 Open the terminal and type: gedit arrayRefadd dot pl ampersand and press Enter.
06:54 'arrayRefadd.pl' file is now open in gedit. Type the code as shown here, in your file.
07:02 The first line initializes an array.
07:06 We have referenced an array with backslash @numarray and assigned to $ref.
07:13 Now, we will see how to access a particular element from the array reference.
07:19 We need to use the array index in square brackets “[ ]” to access the particular value and an arrow operator (“->”) to dereference it.
07:28 The print statement will print the value of index [0].
07:32 push() function adds elements at the last position of an array reference.

In our case, 5, 6, 7 are added to the end of the existing array 1, 2, 3, 4.

07:47 This print statement shows the output, after adding to the array reference.
07:53 pop() function removes an element from the last position of an array reference.
07:58 In our example, 7 will be removed from the existing array reference.
08:03 print statement shows the output after deleting from the array reference.
08:08 Now, press Ctrl+S to save the file.
08:11 Let us execute the program.
08:14 Switch back to the terminal and type: perl arrayRefadd dot pl and press Enter.
08:22 The output is displayed as shown here.
08:26 Now, let us see another sample program to add, remove, and access elements of hash reference.
08:34 On the terminal, type: gedit hashRefadd dot pl ampersand and press Enter.
08:42 This will open the file 'hashRefadd.pl' in gedit.
08:47 Let me explain the sample program.
08:50 I have declared a direct hash reference that can be stored in a scalar variable $weektemp.
08:57 I have used curly brackets to represent the hash reference and the arrow operator to dereference.
09:04 This code stores the temperature values from Monday to Friday.
09:09 I am using the “keys” built-in function to loop through the keys of the hash.
09:15 print statement will print each element of the hash.
09:19 We can access the particular value of an element as shown here.
09:25 print statement will print the temperature on Monday.
09:29 Now, save the file.
09:32 Switch to terminal and type: perl hashRefadd dot pl and press Enter to see the output.
09:41 The hash keys and hash values are stored in a random order.
09:46 The displayed output is not related to the order in which they were added.
09:52 With this, we come to the end of this tutorial. Let us summarize.
09:57 In this tutorial, we learnt about:
  • Scalar References
  • Array References
  • Hash References
  • Dereferences and
  • How to add, remove, access elements of array/hash references with examples.
10:14 Here is an assignment for you. Add new keys “Saturday” and “Sunday” in hash weektemp, in our hashRefadd dot pl file.
10:24 Delete key “Saturday” at the end.
10:27 Print hash weektemp.
10:30 Save and execute the program. Now check the result.
10:35 The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

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10:51 Spoken Tutorial project is funded by NMEICT, MHRD, Government of India.

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11:02 This is Nirmala Venkat from IIT Bombay, signing off. Thanks for watching.

Contributors and Content Editors

Jyotisolanki, PoojaMoolya

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