Sandhya.np14 at 05:43, 25 July 2019

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Sandhya.np14 at 05:42, 25 July 2019

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Sandhya.np14 at 05:06, 25 July 2019

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Sandhya.np14 at 12:11, 24 July 2019

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Sandhya.np14 at 11:39, 24 July 2019

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Sandhya.np14 at 06:28, 11 July 2019

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Sandhya.np14 at 06:28, 11 July 2019

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Sandhya.np14 at 06:28, 11 July 2019

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Sandhya.np14 at 06:26, 11 July 2019

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PoojaMoolya: Created page with " {| border=1 | '''Time''' | '''Narration''' |- | 00:01 |Hello and Welcome to this Spoken Tutorial on '''User-defined function''' in '''awk''..."

2018-12-14T06:47:25Z

Created page with " {| border=1 | <center>'''Time'''</center> | <center>'''Narration'''</center> |- | 00:01 |Hello and Welcome to this Spoken Tutorial on '''User-defined function''' in '''awk''..."

New page

{| border=1
| <center>'''Time'''</center>
| <center>'''Narration'''</center>

|-
| 00:01
|Hello and Welcome to this Spoken Tutorial on '''User-defined function''' in '''awk'''.

|-
| 00:07
| In this tutorial we will learn about- The syntax of '''function definition'''

'''Function call '''and '''Return statement'''

|-
| 00:17
|We will do this through some examples.

|-
| 00:21
| To record this tutorial, I am using '''Ubuntu Linux '''16.04 '''Operating System '''and '''gedit text editor '''3.20.1

|-
| 00:34
| You can use any text editor of your choice.

|-
| 00:38
| To practice this tutorial, you should have gone through the earlier '''awk''' tutorials on this website.

|-
| 00:45
| You should have some knowledge of any programming language like '''C''' or '''C++'''.

|-
| 00:52
| If not, then please go through the corresponding tutorials on our website.

|-
| 00:58
| The files used in this tutorial are available in the '''Code Files''' link on this tutorial page.

Please download and extract them.

|-
| 01:08
| Now let us learn about '''user defined functions.'''

The '''function '''syntax is as follows.

|-
| 01:16
| And the syntax is self-explanatory.

|-
| 01:20
| Here the '''keyword function '''is mandatory.

|-
| 01:24
| To '''call '''a '''function''', write the name of the '''function, '''followed by the '''arguments '''in parentheses.

|-
| 01:31
| Note: '''space '''is not allowed between the '''function '''name and the '''open parentheses '''of the '''argument.'''

|-
| 01:39
| We will see one example now.

|-
| 01:42
|In our '''awkdemo.txt file''', the sixth '''field''' represents '''stipend'''.

|-
| 01:47
|Assume that '''stipend '''is either zero or consists of four '''digits'''.

|-
| 01:54
|Suppose, '''stipend '''is 8900.

Print it as 8 thousand 9 hundred in words.

|-
| 02:03
| If stipend is 0, print as zero in words.

|-
| 02:08
| I have already written the code in a file named '''user_function.awk'''

|-
| 02:15
| Here I have written a '''function '''named '''changeit''' with a single '''argument argval. '''

|-
| 02:23
|Here '''argval''' is basically our sixth '''field '''which is '''stipend'''.

|-
| 02:29
| Inside the '''function''', the first the code will check if '''argval '''is '''zero''' or not.

|-
| 02:36
| If yes, it will print '''“Zero”''' in words.

|-
| 02:40
| If not, then '''else '''part of the code will be executed.

|-
| 02:46
| In the '''else '''part, first we will extract each digit one by one using the '''substring function.'''

|-
| 02:54
|And we'll store the values in an '''array a '''at different '''indices.'''

|-
| 03:00
| For example, '''a[1] ''' will give the first '''digit '''from left hand side or the '''thousand’s place digit.'''

|-
| 03:08
|Since we have only four '''digits''', I have used four indices.

|-
| 03:13
| Next, we will check whether the '''elements '''are not equal to zero.

And print them in a proper order.

|-
| 03:21
| At the end, we print a '''backslash n '''character, to provide a new '''line break''' in the output.

|-
| 03:28
| Then inside the '''awk script''', we have printed '''dollar 2''', which is the second '''field '''that is '''name'''.

|-
| 03:35
| Then we call the '''function changeit '''with the '''parameter dollar 6,''' which is '''stipend'''.

Let’s execute the file.

|-
| 03:43
| Switch to the '''terminal'''.

Next go to the folder where you have downloaded and extracted the file, using '''cd command.'''

|-
| 03:53
| Now type the following '''command '''and press''' Enter.'''

|-
| 04:00
| We get the output as expected.

|-
| 04:03
| A '''user-defined function '''can also include a '''return statement. '''

|-
| 04:08
|This '''statement '''returns '''control '''to the '''calling '''part of the '''awk program'''.

|-
| 04:13
|It can also be used to return a value for use in the rest of the '''awk program. '''

|-
| 04:20
| It looks like this:'''return space expression'''

Here the '''expression '''part is optional.

|-
| 04:29
| Let’s write a '''function '''to return '''average '''of an '''array'''.

|-
| 04:34
| I have written the code in the file '''average.awk'''

Let’s view the contents.

|-
| 04:41
| We have defined a '''function named avg''' for this purpose.

|-
| 04:46
|It has five '''parameters'''.

'''arr''' is the '''array''' for which the '''average''' is to be calculated.

|-
| 04:55
|'''i''' is '''array loop variable.'''

|-
| 04:58
|'''sum''' is the summation of all '''array elements.'''

|-
| 05:03
|'''n''' indicates the number of '''elements '''in '''array.'''

|-
| 05:07
|'''ret''' represents the '''variable '''to be returned from the '''function avg.'''

'''ret''' will store the calculated '''average'''.

|-
| 05:17
| The extra space before '''i '''indicates that the '''variables i, sum, n '''and '''ret '''are '''local variables. '''

|-
| 05:27
|Actually, the '''local variables '''are not intended to be '''arguments'''.

|-
| 05:32
|You should follow this convention when defining '''functions'''.

|-
|05:36
| Inside the '''for loop, '''we have calculated the total number and summation of '''array elements.'''

|-
| 05:43
| We have calculated the '''average '''by dividing summation with the total number of '''elements.'''

And stored that value in '''variable ret.'''

|-
| 05:54
|This '''function avg() '''returns the value of the '''variable ret.'''

|-
| 06:01
| Inside the '''BEGIN section, '''we have defined '''array nums '''with 5 different numbers.

|-
|06:07
| In the '''print statement''', we call the '''function avg() '''with one '''argument''', which is the '''array name.'''

|-
| 06:14
|So, you do not have to pass '''local variables '''as '''arguments'''.

|-
| 06:20
| Switch back to the terminal. Let me clear the terminal.

|-
| 06:26
| Type the following command- '''awk space hyphen f space average dot awk'''

Press '''Enter.'''

|-
| 06:37
| We get the output as 3.6.

You can validate it by using a calculator.

|-
| 06:44
| Let us look at one more example.

|-
| 06:47
| I have written a code to '''reverse '''a '''string '''and named it as '''reverse.awk'''

'''recursive function '''is used to '''reverse '''a '''string.'''

|-
| 06:57
|Pause the video here and look at the code to understand how the control flows.

Then execute it to see the output.

|-
| 07:07
| As an assignment, use the''' function rev''' to '''reverse''' the '''Roll number field '''in '''awkdemo.txt file.'''

|-
| 07:16
|For example, if the roll number is '''A001''', output should be '''100A.'''

|-
| 07:24
|The code for the same is provided as '''reverse_roll.awk''' in the '''Code Files''' link.

|-
| 07:31
| This brings us to the end of this tutorial.

Let us summarize.
|-
| 07:36
| In this tutorial we learnt about- The syntax of '''function definition'''

|-
| 07:41
| '''Function call '''and '''Return statement'''

|-
| 07:45
| As an assignment- 1. Write a '''function '''to create a '''transpose '''of a '''2D matrix.'''

|-
| 07:52
| Write a '''function '''to '''return '''the minimum value '''element '''from an''' array'''.

|-
| 07:58
| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.

|-
| 08:06
| The '''Spoken Tutorial Project''' team conducts workshops using spoken tutorials.

And gives certificates on passing online tests.

|-
| 08:16
|For more details, please write to us.

|-
| 08:20
| Please post your timed queries in this forum.

|-
| 08:24
| Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

|-
| 08:36
| The script has been contributed by Antara.

And this is Praveen from IIT Bombay signing off.

Thank you for joining

|}

@@ Line 24: / Line 24: @@
 | 00:21
 | To record this tutorial, I am using:
-'''Ubuntu Linux '''16.04 '''Operating System '''and
+'''Ubuntu Linux 16.04 Operating System '''and
-'''gedit text editor '''3.20.1
+'''gedit text editor 3.20.1'''
 |-

@@ Line 182: / Line 182: @@
 |-
 | 04:20
-| It looks like this:'''return space expression'''.
+| It looks like this: '''return space expression'''.
 Here, the '''expression '''part is optional.

@@ Line 15: / Line 15: @@
 '''function call '''and
-'''Return''' statement.
+''''Return' statement'''.
 |-
@@ Line 82: / Line 82: @@
 |-
 | 01:47
-|Assume that '''stipend '''is either zero or consists of four '''digits'''.
+|Assume that '''stipend '''is either zero or consists of four digits.
 |-

@@ Line 13: / Line 13: @@
 syntax of '''function''' definition,
 '''function call '''and
 '''Return''' statement.

@@ Line 312: / Line 312: @@
 | 07:36
 | In this tutorial we learnt about-
-syntax of function definition,
+syntax of '''function''' definition,
 |-

@@ Line 170: / Line 170: @@
 |-
 | 04:03
-| A '''user-defined function '''can also include a '''return statement. '''
+| An '''user-defined function '''can also include a '''return statement. '''
 |-

@@ Line 324: / Line 324: @@
 | 07:45
 | As an assignment-
-. Write a '''function '''to create a '''transpose '''of a '''2D matrix.'''
+Write a '''function '''to create a '''transpose of a 2D matrix.'''
 |-
 | 07:52
-| Write a '''function '''to '''return '''the minimum value '''element '''from an''' array'''.
+| Write a function to return the '''minimum value element '''from an''' array'''.
 |-

Linux-AWK/C2/User-Defined-Functions-in-awk/English-timed - Revision history

Sandhya.np14 at 05:43, 25 July 2019

Sandhya.np14 at 05:42, 25 July 2019

Sandhya.np14 at 05:06, 25 July 2019

Sandhya.np14 at 12:11, 24 July 2019

Sandhya.np14 at 11:39, 24 July 2019

Sandhya.np14 at 06:28, 11 July 2019

Sandhya.np14 at 06:28, 11 July 2019

Sandhya.np14 at 06:28, 11 July 2019

Sandhya.np14 at 06:26, 11 July 2019

PoojaMoolya: Created page with " {| border=1 | '''Time''' | '''Narration''' |- | 00:01 |Hello and Welcome to this Spoken Tutorial on '''User-defined function''' in '''awk''..."