Difference between revisions of "PERL/C3/Sample-PERL-program/English-timed"

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|-
 
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|00:06
 
|00:06
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|In this tutorial we will learn to  
+
|In this tutorial, we will learn to include all the major topics we covered so far  
−
 
+
in a sample Perl program.
−
* include all the major topics we covered so far
+
−
* in a sample Perl program
+
  
 
|-
 
|-
 
|00:14
 
|00:14
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|To record this tutorial, I am using
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|To record this tutorial, I am using:
−
 
+
 
* '''Ubuntu Linux 12.04''' operating system
 
* '''Ubuntu Linux 12.04''' operating system
−
* '''Perl 5.14.2'''
+
* '''Perl 5.14.2''' and
−
* and the''' gedit''' Text Editor
+
* the''' gedit''' Text Editor.
  
 
|-
 
|-
 
|00:25
 
|00:25
−
|You can use any text editor of your choice.
+
|You can use any '''text editor''' of your choice.
  
 
|-
 
|-
 
|00:29
 
|00:29
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|As a prerequisite, you should have working knowledge of '''Perl''' Programming.
+
|As a prerequisite, you should have working knowledge of '''Perl''' programming.
  
 
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|-
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|-
 
|-
 
|00:46
 
|00:46
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|'''Weather dot pm''' is a''' module''' file that has a complex data structure to hold the data required for this program.
+
|'''Weather dot pm''' is a''' module''' file that has a complex data-structure to hold the data required for this program.
  
 
|-
 
|-
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|-
 
|-
 
|01:18
 
|01:18
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|Now let us see our sample '''Perl '''program '''Weather dot pm.'''
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|Now, let us see our sample '''Perl '''program '''Weather dot pm.'''
  
 
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|-
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|-
 
|-
 
|01:29
 
|01:29
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|'''Perl '''implements '''namespace '''using the''' package keyword.'''
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|'''Perl '''implements '''namespace '''using the''' package''' keyword.
  
 
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|-
 
|01:34
 
|01:34
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|'''BEGIN''' block is compiled and executed before the main program.
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|'''BEGIN''' block is compiled and executed before the '''main''' program.
  
 
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|-
 
|-
 
|01:48
 
|01:48
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|'''At the rate EXPORT''' and''' at the rate EXPORT underscore OK''' are the two main variables used during export operation.
+
|'''At the rate EXPORT''' and''' at the rate EXPORT underscore OK''' are the two main variables used during '''export''' operation.
  
 
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|-
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|-
 
|-
 
|02:14
 
|02:14
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|Here I have used''' references''' to create complex data structures to hold the data required for a weather report.
+
|Here, I have used''' references''' to create complex data-structures to hold the data required for a weather report.
  
 
|-
 
|-
 
|02:24
 
|02:24
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|'''$weather_report''' is a''' hash reference'''. “'''place'''” and “'''nstate'''” has the scalar values.
+
|'''$weather_report''' is a''' hash reference'''. “'''place'''” and “'''nstate'''” have the scalar values.
  
 
|-
 
|-
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|-
 
|-
 
|02:48
 
|02:48
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|“'''record underscore time'''” is an''' array reference''' with two index values.
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|“'''record underscore time'''” is an''' array reference''' with two '''index''' values.
  
 
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|-
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|-
 
|-
 
|03:01
 
|03:01
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|This function prints the header information such as header of the report, place, state and current date.
+
|This '''function''' prints the '''header''' information such as header of the report, place, state and current date.
  
 
|-
 
|-
 
|03:10
 
|03:10
−
|Now let us see the next function''' display underscore daily underscore report.'''
+
|Now, let us see the next function''' display underscore daily underscore report.'''
  
 
|-
 
|-
 
|03:16
 
|03:16
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|This '''function '''prints the daily report on the screen depending upon the weekday input.
+
|This '''function '''prints the daily report on the screen, depending upon the weekday input.
  
 
|-
 
|-
 
|03:22
 
|03:22
−
| We retrieve the parameter passed into a '''subroutine''' using the''' shift function.'''
+
| We retrieve the parameter passed into a '''subroutine''' using the''' shift''' function.
  
 
|-
 
|-
 
|03:27
 
|03:27
−
|I have used the''' trim function''' to remove the leading and trailing spaces of the parameter value.
+
|I have used the''' trim() '''function to remove the leading and trailing spaces of the '''parameter''' value.
  
 
|-
 
|-
 
|03:34
 
|03:34
−
| Here is the code for the '''trim function'''.
+
| Here is the code for the '''trim()''' function.
  
 
|-
 
|-
 
|03:37
 
|03:37
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| '''Lc function''' returns a lowercase version of the given input.
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| '''Lc()''' function returns a lowercase version of the given input.
  
 
|-
 
|-
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|-
 
|-
 
|03:45
 
|03:45
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| The week day - passed as parameter from the main program, is assigned to a''' local variable dollar week underscore day'''.
+
| The 'week day'- passed as parameter from the main program, is assigned to a local variable '''dollar week underscore day'''.
  
 
|-
 
|-
 
|03:55
 
|03:55
−
| The following '''print statements''' will print the data corresponding to a specified week day.
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| The following '''print statement'''s will print the data corresponding to a specified week day.
  
 
|-
 
|-
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|-
 
|-
 
|04:20
 
|04:20
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| If it is an '''array,''' we need to use the square brackets with the index values.
+
| If it is an '''array,''' we need to use the square brackets with the '''index value'''s.
  
 
|-
 
|-
 
|04:26
 
|04:26
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| '''return function''' of '''Perl''' returns a value.
+
| '''return''' function of '''Perl''' returns a value.
  
 
|-
 
|-
 
|04:29
 
|04:29
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|This can be used to check the status of the '''function''' in the main program.
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|This can be used to check the status of the '''function''' in the '''main''' program.
  
 
|-
 
|-
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|04:40
 
|04:40
  
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|This '''function''' will print the report output to a file.
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|This '''function''' will print the '''report output''' to a file.
  
 
|-
 
|-
 
|04:45
 
|04:45
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|The''' open function''' with the greater than (>) symbol defines the''' WRITE''' mode.
+
|The''' open''' function with the greater than (>) symbol defines the''' WRITE''' mode.
  
 
|-
 
|-
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|-
 
|-
 
|05:30
 
|05:30
−
|Now let us see - a '''Perl '''program '''weather underscore report dot pl ''' where we will make use of this '''module '''file '''Weather dot pm'''.
+
|Now, let us see - a '''Perl '''program '''weather underscore report dot pl ''' where we will make use of this '''module '''file '''Weather dot pm'''.
  
 
|-
 
|-
 
|05:40
 
|05:40
−
|Here, '''use strict''' and''' use warnings''' are compiler flags that helps to avoid common programming mistakes.
+
|Here, '''use strict''' and''' use warnings''' are compiler flags that help to avoid common programming mistakes.
  
 
|-
 
|-
 
|05:48
 
|05:48
−
| '''use Weather semicolon.''' Here '''Weather '''is a''' module''' name which I have used in this program.
+
| '''use Weather''' semicolon. Here, '''Weather '''is a''' module''' name which I have used in this program.
  
 
|-
 
|-
 
|05:56
 
|05:56
−
|We have already seen that the '''functions''' required for this program have been stored in this''' module'''.
+
|We have already seen that the functions required for this program have been stored in this''' module'''.
  
 
|-
 
|-
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|06:14
 
|06:14
 
|The user has to enter an option to print the  daily weather report of a particular week day,  
 
|The user has to enter an option to print the  daily weather report of a particular week day,  
−
daily weather report of a particular week day to an output file,  weekly weather report
+
daily weather report of a particular week day to an output file,  weekly weather report.
  
 
|-
 
|-
 
|06:27
 
|06:27
−
|If option '''1''' is typed, it will ask the user to enter the day of a week.
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|If option '1' is typed, it will ask the user to enter the day of a week.
  
 
|-
 
|-
 
|06:32
 
|06:32
−
|The '''diamond '''operator will read from''' STDIN''', that is from the keyboard.
+
|The '''diamond '''operator will read from''' STDIN''', that is, from the keyboard.
  
 
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|-
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|-
 
|-
 
|06:56
 
|06:56
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|We have exported all '''functions''' in '''Weather dot pm''' with “'''use Weather'''” statement in this file.
+
|We have exported all functions in '''Weather dot pm''' with “'''use Weather'''” statement in this file.
  
 
|-
 
|-
 
|07:03
 
|07:03
−
|So, no need to refer the '''functions''' within a package using the '''colon colon (::)package qualifier'''
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|So, no need to refer the functions within a package using the '''colon colon (::)package qualifier'''
  
 
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|-
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|-
 
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|07:13
 
|07:13
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|If option 2 is typed, it will prompt the user to enter the day of a week.
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|If option '2' is typed, it will prompt the user to enter the day of a week.
  
 
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|-
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|07:27
 
|07:27
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| '''return '''value from the '''function''' is stored in the variable '''dollar result'''.
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| '''return '''value from the function is stored in the variable '''dollar result'''.
  
 
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|07:46
 
|07:46
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|If option 3 is typed, it prints the weather report for the whole week.
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|If option '3' is typed, it prints the weather report for the whole week.
  
 
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|-
 
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|08:11
 
|08:11
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|If any option, other than the ones specified, is given, the''' print statement''' says “'''Incorrect option'''”.
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|If any option other than the ones specified is given, the''' print statement''' says “'''Incorrect option'''”.
  
 
|-
 
|-
 
|08:19
 
|08:19
−
|Here the exit value of 0 indicates the program ran successfully.
+
|Here, the exit value of '0' indicates the program ran successfully.
  
 
|-
 
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|08:25
 
|08:25
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|The exit value other than 0 means an error of some kind has occurred.  
+
|The exit value other than '0' means an error of some kind has occurred.  
  
 
|-
 
|-
 
|08:31
 
|08:31
−
|Now let us execute the program.
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|Now, let us execute the program.
  
 
|-
 
|-
 
|08:34
 
|08:34
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|Switch to the '''terminal '''and type '''perl weather underscore report dot pl''' and press''' Enter'''
+
|Switch to the '''terminal '''and type '''perl weather underscore report dot pl''' and press''' Enter'''.
  
 
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|08:45
 
|08:45
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|Type '''1 '''and press '''Enter.'''
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|Type '1 'and press '''Enter.'''
  
 
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|08:48
 
|08:48
−
|We are prompted to enter a day of the week. I'll type ''''monday'''' and press '''Enter'''.
+
|We are prompted to enter a day of the week. I'll type "monday" and press '''Enter'''.
  
 
|-
 
|-
 
|08:56  
 
|08:56  
−
|This is the header output generated from the '''function display underscore header().'''
+
|This is the '''header output''' generated from the '''function display underscore header().'''
  
 
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|09:17
 
|09:17
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|At the prompt, we have to type any week day. I will type ‘'''wednesday’''' and press '''Enter'''.
+
|At the prompt, we have to type any week day. I will type "wednesday" and press '''Enter'''.
  
 
|-
 
|-
 
|09:25
 
|09:25
−
|We can see a message '''Please check the file wednesday dot txt for report output '''.
+
|We can see a message: '''Please check the file wednesday dot txt for report output '''.
  
 
|-
 
|-
 
|09:32
 
|09:32
−
|The output has been written to this text file.  Let us open the file and check the content.
+
|The output has been written to this text file.  Let us open the file and check the contents.
  
 
|-
 
|-
 
|09:38
 
|09:38
−
|Type '''gedit wednesday dot txt''' and press''' Enter.'''
+
|Type: '''gedit wednesday dot txt''' and press''' Enter.'''
  
 
|-
 
|-
 
|09:44
 
|09:44
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|The output file has been created with the entered week day name with '''txt''' extension.
+
|The output file has been created with the entered week day name with 'txt' extension.
  
 
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|-
 
|09:51
 
|09:51
−
|Now let us check the next option.
+
|Now, let us check the next option.
  
 
|-
 
|-
 
|09:54
 
|09:54
−
|Switch to the terminal and type''' perl weather underscore report dot pl '''and press''' Enter'''
+
|Switch to the terminal and type:''' perl weather underscore report dot pl '''and press''' Enter'''.
  
 
|-
 
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|10:00
 
|10:00
−
|Type '''3 '''and press '''Enter.'''
+
|Type '3 'and press '''Enter.'''
  
 
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|10:13
 
|10:13
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|So the displayed output is not related to the order in which they were added.
+
|So, the displayed output is not related to the order in which they were added.
  
 
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|10:24
 
|10:24
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| In this tutorial we have seen a sample '''Perl''' program by covering main topics of our previous tutorials.  
+
| In this tutorial, we have seen a sample '''Perl''' program by covering main topics of our previous tutorials.  
  
 
|-
 
|-
 
|10:32
 
|10:32
−
| As an assignment,  Write a similar '''Perl''' program '''employee underscore report.pl''' for displaying employee salary, designation, department, leave_balance details.
+
| As an assignment,  write a similar '''Perl''' program '''employee underscore report.pl''' for displaying '''employee salary, designation, department, leave_balance''' details.
  
 
|-
 
|-
 
|10:45
 
|10:45
−
|Pass Employee ID or Employee name as input.
+
|Pass '''Employee ID''' or '''Employee name''' as input.
  
 
|-
 
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|10:56
 
|10:56
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| The video at the following link summarize the spoken tutorial. Please download and watch it
+
| The video at the following link summarize the '''spoken tutorial'''. Please download and watch it.
  
 
|-
 
|-

Revision as of 17:24, 27 December 2015

Time
Narration
00:01 Welcome to the Spoken Tutorial on Sample PERL program.
00:06 In this tutorial, we will learn to include all the major topics we covered so far

in a sample Perl program.

00:14 To record this tutorial, I am using:
  • Ubuntu Linux 12.04 operating system
  • Perl 5.14.2 and
  • the gedit Text Editor.
00:25 You can use any text editor of your choice.
00:29 As a prerequisite, you should have working knowledge of Perl programming.
00:34 If not, then go through the relevant Perl spoken tutorials on this website.
00:39 The sample Perl program will give the output of various weather forecast reports of a region.
00:46 Weather dot pm is a module file that has a complex data-structure to hold the data required for this program.
00:54 It also contains various functions to generate the report.
00:59 Weather underscore report dot pl is the Perl program which makes use of this module file to give the required output.
01:08 The same code files are available under this video on our website.
01:13 Download and unzip the files provided in the code file link.
01:18 Now, let us see our sample Perl program Weather dot pm.
01:24 The block of code in this program is under the namespace Weather.
01:29 Perl implements namespace using the package keyword.
01:34 BEGIN block is compiled and executed before the main program.
01:40 Export allows to export the functions and variables of modules to user's namespace.
01:48 At the rate EXPORT and at the rate EXPORT underscore OK are the two main variables used during export operation.
01:57 At the rate EXPORT contains list of subroutines and variables of the module.
02:03 These will be exported into the caller namespace.
02:07 At the rate EXPORT underscore OK does export of symbols on demand basis.
02:14 Here, I have used references to create complex data-structures to hold the data required for a weather report.
02:24 $weather_report is a hash reference. “place” and “nstate” have the scalar values.
02:32 “weekly” is hash of hash references.
02:37 *Each week day has four keys - 
 max underscore temp, 
 min underscore temp, 
 sunrise,
 sunset.
02:48 “record underscore time” is an array reference with two index values.
02:54 I have a few subroutines to display the weather report of various options.

Let us see one by one.

03:01 This function prints the header information such as header of the report, place, state and current date.
03:10 Now, let us see the next function display underscore daily underscore report.
03:16 This function prints the daily report on the screen, depending upon the weekday input.
03:22 We retrieve the parameter passed into a subroutine using the shift function.
03:27 I have used the trim() function to remove the leading and trailing spaces of the parameter value.
03:34 Here is the code for the trim() function.
03:37 Lc() function returns a lowercase version of the given input.
03:42 This is used to avoid case-sensitivity.
03:45 The 'week day'- passed as parameter from the main program, is assigned to a local variable dollar week underscore day.
03:55 The following print statements will print the data corresponding to a specified week day.
04:01 We are using the arrow operator to dereference a value in $weather underscore report.
04:09 When working with references, we have to understand the data type we are dereferencing.
04:15 If it is a hash, we need to pass the key in curly braces.
04:20 If it is an array, we need to use the square brackets with the index values.
04:26 return function of Perl returns a value.
04:29 This can be used to check the status of the function in the main program.
04:36 The next function is write underscore daily underscore report.
04:40 This function will print the report output to a file.
04:45 The open function with the greater than (>) symbol defines the WRITE mode.
04:50 Filename is created with the weekday name and dot txt extension.
04:56 The print statements will print the corresponding data of a specified week day to a file.
05:02 This prints the weekly report.
05:05 I have declared a foreach loop to loop through each weekday of the hash reference.
05:11 I have used curly brackets to represent the hash reference and the arrow operator to dereference.
05:18 I am using the “keys” in-built function to loop through the keys of the hash.
05:23 display underscore daily underscore report function will print each element of the hash.
05:30 Now, let us see - a Perl program weather underscore report dot pl where we will make use of this module file Weather dot pm.
05:40 Here, use strict and use warnings are compiler flags that help to avoid common programming mistakes.
05:48 use Weather semicolon. Here, Weather is a module name which I have used in this program.
05:56 We have already seen that the functions required for this program have been stored in this module.
06:03 It is not required to give the dot pm file extension here.
06:08 In this program, I'll print different reports depending upon the given options.
06:14 The user has to enter an option to print the daily weather report of a particular week day,

daily weather report of a particular week day to an output file, weekly weather report.

06:27 If option '1' is typed, it will ask the user to enter the day of a week.
06:32 The diamond operator will read from STDIN, that is, from the keyboard.
06:38 For example, if the user enters 'monday', then it is assigned to a variable dollar dayoption, which is a local variable.
06:47 Next, we can see that we are calling two functions-
  • display_header() and
  • display_daily_report().
06:56 We have exported all functions in Weather dot pm with “use Weather” statement in this file.
07:03 So, no need to refer the functions within a package using the colon colon (::)package qualifier
07:10 Now let's see the next option.
07:13 If option '2' is typed, it will prompt the user to enter the day of a week.
07:19 $dayoption is passed as the input parameter to the function write underscore daily underscore report.
07:27 return value from the function is stored in the variable dollar result.
07:33 Print statement asks the user to check the text file for the output.
07:38 The filename is created with the day of the week dot txt as output file.
07:46 If option '3' is typed, it prints the weather report for the whole week.
07:51 display underscore weekly underscore report is the function name of the weekly report.
07:57 This print statement draws a horizontal line for the specified number of times.
08:02 This is just to give a good look to the report.
08:06 Lastly, if the option is 4, it will quit the program.
08:11 If any option other than the ones specified is given, the print statement says “Incorrect option”.
08:19 Here, the exit value of '0' indicates the program ran successfully.
08:25 The exit value other than '0' means an error of some kind has occurred.
08:31 Now, let us execute the program.
08:34 Switch to the terminal and type perl weather underscore report dot pl and press Enter.
08:41 We can see four options on the screen.
08:45 Type '1 'and press Enter.
08:48 We are prompted to enter a day of the week. I'll type "monday" and press Enter.
08:56 This is the header output generated from the function display underscore header().
09:02 Now, we can see the weather report of Monday.
09:06 Now I'll again execute the program once again to demonstrate the other options.
09:13 Type 2 and press Enter.
09:17 At the prompt, we have to type any week day. I will type "wednesday" and press Enter.
09:25 We can see a message: Please check the file wednesday dot txt for report output .
09:32 The output has been written to this text file. Let us open the file and check the contents.
09:38 Type: gedit wednesday dot txt and press Enter.
09:44 The output file has been created with the entered week day name with 'txt' extension.
09:51 Now, let us check the next option.
09:54 Switch to the terminal and type: perl weather underscore report dot pl and press Enter.
10:00 Type '3 'and press Enter.
10:04 This time, we can see the weekly weather report.
10:08 The hash keys and hash values are stored in a random order.
10:13 So, the displayed output is not related to the order in which they were added.
10:19 With this, we come to the end of this tutorial. Let us summarize.
10:24 In this tutorial, we have seen a sample Perl program by covering main topics of our previous tutorials.
10:32 As an assignment, write a similar Perl program employee underscore report.pl for displaying employee salary, designation, department, leave_balance details.
10:45 Pass Employee ID or Employee name as input.
10:50 Write the required functions in the module Employee dot pm file.
10:56 The video at the following link summarize the spoken tutorial. Please download and watch it.
11:03 We conduct workshops and give certificates for those who pass our online tests.

For more details, please write to us.

11:12 Spoken Tutorial project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

11:25 This is Nirmala Venkat from IIT Bombay, signing off. Thanks for watching.

Contributors and Content Editors

PoojaMoolya, Sandhya.np14

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