Difference between revisions of "Advance-C/C2/Storage-class-specifiers/English-timed"

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{| Border=1
 
{| Border=1
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! <center>Time</center>
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| '''Time'''
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! <center>Narration</center>
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| '''Narration'''
  
 
|-
 
|-
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| 00:07
 
| 00:07
 
| In this tutorial, We will learn about:
 
| In this tutorial, We will learn about:
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* '''Storage class specifiers'''
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'''Storage class specifiers'''
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* '''auto''' keyword
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'''auto''' keyword
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* '''static''' keyword  
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'''static''' keyword  
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* '''extern''' keyword
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'''extern''' keyword
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* '''register''' keyword, with the help of an example.
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'''register''' keyword, with the help of an example.
  
 
|-
 
|-
 
| 00:22
 
| 00:22
 
| For this tutorial, I am using:
 
| For this tutorial, I am using:
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* '''Ubuntu Operating system''' version '''11.10''' and  
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'''Ubuntu Operating system''' version '''11.10''' and  
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* '''gcc Compiler''' version '''4.6.1''' on Ubuntu.
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'''gcc Compiler''' version '''4.6.1''' on Ubuntu.
  
 
|-
 
|-
 
| 00:34
 
| 00:34
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| To follow this tutorial, you should be familiar with 'C' tutorials.
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| To follow this tutorial, you should be familiar with '''C''' tutorials.
  
 
|-
 
|-
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|-
 
|-
 
| 00:57
 
| 00:57
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|* How to store the variable
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| How to store the variable
  
 
|-
 
|-
 
| 00:59
 
| 00:59
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|* What is the initial value of the variable
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| What is the initial value of the variable
  
 
|-
 
|-
 
| 01:03
 
| 01:03
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|* Life time of the variable.
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|Life time of the variable.
  
 
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|-
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| 01:13
 
| 01:13
 
| Types of storage class specifiers are:
 
| Types of storage class specifiers are:
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* '''auto '''
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'''auto '''
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* '''static '''
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'''static '''
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* '''extern '''
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'''extern '''
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* '''register '''.
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'''register '''.
  
 
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| 02:14
 
| 02:14
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| Here, we have declared variable 'i' as '''auto int'''. It has a '''local''' scope.
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| Here, we have declared variable '''i''' as '''auto int'''. It has a '''local''' scope.
  
 
|-
 
|-
 
| 02:21
 
| 02:21
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| Then we display value of 'i' using''' printf.'''
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| Then we display value of '''i''' using''' printf.'''
  
 
|-
 
|-
 
| 02:26
 
| 02:26
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| Value of 'i' is incremented here.
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| Value of '''i''' is incremented here.
  
 
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| 03:02
 
| 03:02
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| I will cut this declaration and initialization from here and paste it over here.
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| I will cut this declaration and initialization from here and paste it over here.Click on '''Save'''.
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Click on '''Save'''.
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|-
 
|-
 
| 03:14
 
| 03:14
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| Let us execute on the '''terminal'''. Press the up-arrow key twice.
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| Let us execute on the '''terminal'''. Press the up-arrow key twice. Press '''Enter'''.
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Press '''Enter'''.
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|-
 
|-
 
| 03:22
 
| 03:22
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| We get an error: "file-scope declaration of '''i''' specifies '''auto'''".
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| We get an error: '''"file-scope declaration of '''i''' specifies '''auto'''".
  
 
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|-
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|-
 
|-
 
| 04:07
 
| 04:07
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| This is because we have initialized the value of 'i' as zero.
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| This is because we have initialized the value of '''i''' as zero.
  
 
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|-
 
| 04:35
 
| 04:35
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| Value of the variable persists between different '''function call'''s.
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| Value of the variable persists between different '''function calls'''.
  
 
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|05:10
 
|05:10
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| Now, I will change the initialization of  the variable 'i' to '''static int i equal to zero'''
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| Now, I will change the initialization of  the variable '''i''' to '''static int i equal to zero'''
 
Click on''' Save'''.
 
Click on''' Save'''.
  
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|-
 
|-
 
| 05:46
 
| 05:46
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| The output is displayed as: "0, 1, 2, 3"
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| The output is displayed as: '''0, 1, 2, 3'''
  
 
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|-
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|-
 
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| 06:17
 
| 06:17
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|Definition for '''extern''' variable might be anywhere in the 'C' program.
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|Definition for '''extern''' variable might be anywhere in the '''C''' program.
  
 
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|-
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|-
 
|-
 
| 06:42
 
| 06:42
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|Note that our filename is "extern.c".
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|Note that our filename is '''"extern.c"'''.
  
 
|-
 
|-
 
| 06:47
 
| 06:47
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| I have initialized a variable as '''integer variable 'x'''' to '''10'''.
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| I have initialized a variable as '''integer variable''' '''x''' to '''10'''.
  
 
|-
 
|-
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|-
 
|-
 
|07:03
 
|07:03
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| Using the '''printf''' statements, we will display the values of 'x' and 'y'.
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| Using the '''printf''' statements, we will display the values of '''x''' and '''y'''.This is the '''return''' statement.
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This is the '''return''' statement.
+
  
 
|-
 
|-
 
| 07:12
 
| 07:12
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| We will initialize 'y' to '''50 '''after the '''main()''' function close.
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| We will initialize '''y''' to '''50 '''after the '''main()''' function close.
  
 
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|-
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| 07:40
 
| 07:40
 
| The output is displayed as:
 
| The output is displayed as:
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"The value of x is 10"  
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'''"The value of x is 10"'''
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"The value of y is 50"
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'''"The value of y is 50"'''
  
 
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| 08:37
 
| 08:37
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|Note that the filename is "register.c".
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|Note that the filename is '''register.c'''
  
 
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| 08:59
 
| 08:59
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|This will display the value of 'i'.
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|This will display the value of '''i'''.
  
 
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| 09:25
 
| 09:25
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| You can see, the output is displayed as: "Values stored in register memory 1 2 3 4 5".
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| You can see, the output is displayed as: '''Values stored in register memory 1 2 3 4 5'''.
  
 
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|-
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| 09:39
 
| 09:39
 
| In this tutorial, we learnt-
 
| In this tutorial, we learnt-
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* '''Storage class specifiers'''
+
'''Storage class specifiers'''
−
* '''auto''' keyword
+
'''auto''' keyword
−
* '''static''' keyword
+
'''static''' keyword
−
* '''extern''' keyword
+
'''extern''' keyword
−
* '''register''' keyword.
+
'''register''' keyword.
  
 
|-
 
|-

Latest revision as of 15:42, 20 February 2017

Time Narration
00:01 Welcome to the Spoken Tutorial on Storage class specifiers.
00:07 In this tutorial, We will learn about:

Storage class specifiers auto keyword static keyword extern keyword register keyword, with the help of an example.

00:22 For this tutorial, I am using:

Ubuntu Operating system version 11.10 and gcc Compiler version 4.6.1 on Ubuntu.

00:34 To follow this tutorial, you should be familiar with C tutorials.
00:41 If not, for relevant tutorials, please visit our website which is as shown.
00:47 I will start with an introduction to storage class specifiers.
00:52 Specifiers tell the compiler- * where to store a variable
00:57 How to store the variable
00:59 What is the initial value of the variable
01:03 Life time of the variable.
01:06 The Syntax is: storage_specifier data_type variable _name.
01:13 Types of storage class specifiers are:

auto static extern register .

01:21 Let us start with auto keyword.
01:24 auto keyword declares an automatic variable.
01:28 It has a local scope.
01:30 Keywords are not initialized automatically.
01:34 You should explicitly initialize keywords while declaring.
01:39 Storage-space of keywords is CPU memory.
01:43 Let us see an example. I have a code file; let us go through it.
01:49 Note that our filename is auto.c.
01:54 We have declared a function as “increment()”.
01:58 This is the main() function.
02:00 In the main() function, increment() function is called 4 times.
02:06 Then we have the return 0 statement.
02:10 Let us see the function definition.
02:14 Here, we have declared variable i as auto int. It has a local scope.
02:21 Then we display value of i using printf.
02:26 Value of i is incremented here.
02:30 Let us open the terminal by pressing Ctrl+Alt+T keys simultaneously on your keyboard.
02:38 Type: gcc space auto.c space hyphen o space auto. Press Enter.
02:48 Type: dot slash auto
02:51 The output is zero.
02:54 Now come back to our program.
02:57 Let us initialize the auto variable i above the main() function.
03:02 I will cut this declaration and initialization from here and paste it over here.Click on Save.
03:14 Let us execute on the terminal. Press the up-arrow key twice. Press Enter.
03:22 We get an error: "file-scope declaration of i specifies auto".
03:29 This is because an auto variable is local to the function.
03:34 We cannot initialize it globally.
03:37 Let us fix the error. Come back to our program.
03:42 Delete this; paste it over here.
03:47 Click on Save and execute on the terminal.
03:52 Press the up-arrow key. Recall the previous command.
03:57 Press Enter. Type: dot slash auto. Press Enter.
04:03 Yes, it is working! The output is zero.
04:07 This is because we have initialized the value of i as zero.
04:13 Now, let us see static variable.
04:16 Although we have studied about static variable, in the previous tutorials, I will explain it here briefly.
04:24 'static' variables are initialized to zero.
04:28 They are not destroyed even after program control exits from the block.
04:35 Value of the variable persists between different function calls.
04:41 Storage-space is CPU memory.
04:45 Let us see an example. I will edit the same code file.
04:51 Come back to our program.
04:54 Press Ctrl + Shift + S keys simultaneously.
05:01 Now, I will just change the filename as static. Click on Save.
05:10 Now, I will change the initialization of the variable i to static int i equal to zero

Click on Save.

05:23 Let us see what happens. Execute the file on the terminal.
05:30 Type: gcc space static.c space hyphen o space stat. Press Enter.
05:41 Type: dot slash stat. Press Enter.
05:46 The output is displayed as: 0, 1, 2, 3
05:51 This is because static variables are global variables.
05:56 The scope of static variable is local to the function, they are defined in.
06:03 They do not lose their value between function calls.
06:08 Now, let us learn about extern keyword.
06:12 Scope of extern variable is throughout the main program.
06:17 Definition for extern variable might be anywhere in the C program.
06:23 extern variables are initialized to zero, by default.
06:28 They can be accessed by all functions in the program.
06:33 These are stored in CPU memory.
06:36 Let us see an example.
06:38 I have a code file; let us go through it.
06:42 Note that our filename is "extern.c".
06:47 I have initialized a variable as integer variable x to 10.
06:54 This is the main() function. In the main() function, I have declared an extern integer variable y.
07:03 Using the printf statements, we will display the values of x and y.This is the return statement.
07:12 We will initialize y to 50 after the main() function close.
07:18 Now, switch to the terminal and let us see what will be the output.
07:24 Type: gcc space extern.c space hyphen o space ext. Press Enter.
07:35 Type: dot slash ext. Press Enter.
07:40 The output is displayed as:

"The value of x is 10" "The value of y is 50"

07:48 As we studied, the value of the extern keyword is through out the main program.
07:55 We can define it anywhere in the program.
07:59 Both the statements are justified.
08:02 Now, let us move on to register keyword.
08:06 register variables will be accessed faster than normal variables.
08:13 They are stored in register memory rather than main memory.
08:19 Limited number of variables can be used since register size is very low.
08:25 16 bits, 32 bits or 64 bits.
08:30 Let us see an example now. I have a code file. Let us go through it.
08:37 Note that the filename is register.c
08:42 Here, we have declared register integer variable.
08:47 This variable will be directly stored in the register memory.
08:53 This is the 'for' loop that displays the value of i from 1 to 5.
08:59 This will display the value of i.
09:03 Let us execute the program and see.
09:07 On the terminal, type: gcc space register.c space hyphen o space register
09:17 Press Enter. Type: dot slash register. Press Enter.
09:25 You can see, the output is displayed as: Values stored in register memory 1 2 3 4 5.
09:34 This brings us to the end of this tutorial. Let us summarize.
09:39 In this tutorial, we learnt-

Storage class specifiers auto keyword static keyword extern keyword register keyword.

09:52 As an assignment, write a program to print the sum of first 5 numbers.
09:59 Declare both the keywords auto and static in the program.
10:04 Watch the video available at the link shown below.
10:07 It summarizes the Spoken Tutorial project.
10:11 If you do not have good bandwidth, you can download and watch it.
10:16 The Spoken Tutorial project team: * Conducts workshops using spoken tutorials.
10:22 Gives certificates to those who pass an online test.For more details, please write to contact@spoken-tutorial.org
10:33 Spoken Tutorial project is a part of the Talk to a Teacher project.
10:38 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
10:45 More information on this mission is available at the link shown below:http://spoken-tutorial.org\NMEICT-Intro.
10:52 This is Ashwini Patil from IIT Bombay, signing off. Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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