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Articles by Mohd Mohtashim
Page 7 of 19
GMT Time in Perl
The function gmtime() in Perl works just like localtime() function but the returned values are localized for the standard Greenwich time zone. When called in list context, $isdst, the last value returned by gmtime, is always 0. There is no Daylight Saving Time in GMT.You should make a note on the fact that localtime() will return the current local time on the machine that runs the script and gmtime() will return the universal Greenwich Mean Time, or GMT (or UTC).Try the following example to print the current date and time but on GMT scale −Example#!/usr/local/bin/perl $datestring = gmtime(); print "GMT ...
Read MoreFormat Date and Time in Perl
You can use localtime() function in Perl to get a list of 9-elements and later you can use the printf() function to format date and time based on your requirements as follows −Example#!/usr/local/bin/perl ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(); printf("Time Format - HH:MM:SS"); printf("%02d:%02d:%02d", $hour, $min, $sec);OutputWhen the above code is executed, it produces the following result −Time Format - HH:MM:SS 06:58:52
Read MoreEpoch time in Perl
You can use the time() function in Perl to get epoch time, i.e., the numbers of seconds that have elapsed since a given date, in Unix is January 1, 1970.Example#!/usr/local/bin/perl $epoc = time(); print "Number of seconds since Jan 1, 1970 - $epoc";OutputWhen the above code is executed, it produces the following result −Number of seconds since Jan 1, 1970 - 1361022130You can convert a given number of seconds into date and time string as follows −Example#!/usr/local/bin/perl $datestring = localtime(); print "Current date and time $datestring"; $epoc = time(); $epoc = $epoc - 24 * 60 * 60; # ...
Read MorePOSIX Function strftime() in Perl
You can use the POSIX function strftime() in Perl to format the date and time with the help of the following table. Please note that the specifiers marked with an asterisk (*) are locale-dependent.SpecifierReplaced byExample%aAbbreviated weekday name *Thu%AFull weekday name *Thursday%bAbbreviated month name *Aug%BFull month name *August%cDate and time representation *Thu Aug 23 14:55:02 2001%CA year divided by 100 and truncated to integer (00-99)20%dDay of the month, zero-padded (01-31)23%DShort MM/DD/YY date, equivalent to %m/%d/%y08/23/01%eDay of the month, space-padded ( 1-31)23%FShort YYYY-MM-DD date, equivalent to %Y-%m-%d2001-08-23%gWeek-based year, last two digits (00-99)01%GWeek-based year2001%hAbbreviated month name * (same as %b)Aug%HAn hour in 24h ...
Read MoreDefine and Call a Subroutine in Perl
The general form of a subroutine definition in Perl programming language is as follows −sub subroutine_name { body of the subroutine }The typical way of calling that Perl subroutine is as follows −subroutine_name( list of arguments );In versions of Perl before 5.0, the syntax for calling subroutines was slightly different as shown below. This still works in the newest versions of Perl, but it is not recommended since it bypasses the subroutine prototypes.&subroutine_name( list of arguments );Let's have a look into the following example, which defines a simple function and then call it. Because Perl compiles your program before ...
Read MorePassing Arguments to a Subroutine in Perl
You can pass various arguments to a Perl subroutine like you do in any other programming language and they can be accessed inside the function using the special array @_. Thus the first argument to the function is in $_[0], the second is in $_[1], and so on.You can pass arrays and hashes as arguments like any scalar but passing more than one array or hash normally causes them to lose their separate identities. So we will use references ( explained in the next chapter ) to pass an array or hash.Let's try the following example, which takes a list ...
Read MorePassing Lists to Subroutines in Perl
Because the @_ variable is an array in Perl, it can be used to supply lists to a subroutine. However, because of the way in which Perl accepts and parses lists and arrays, it can be difficult to extract the individual elements from @_. If you have to pass a list along with other scalar arguments, then make list as the last argument as shown below −Example#!/usr/bin/perl # Function definition sub PrintList { my @list = @_; print "Given list is @list"; } $a = 10; @b = (1, 2, 3, 4); # Function call with list parameter ...
Read MorePassing Hashes to Subroutines in Perl
When you supply a hash to a Perl subroutine or operator that accepts a list, then the hash is automatically translated into a list of key/value pairs. For example −Example#!/usr/bin/perl # Function definition sub PrintHash { my (%hash) = @_; foreach my $key ( keys %hash ) { my $value = $hash{$key}; print "$key : $value"; } } %hash = ('name' => 'Tom', 'age' => 19); # Function call with hash parameter PrintHash(%hash);OutputWhen the above program is executed, it produces the following result −name : Tom age : 19
Read MoreReturning Value from a Subroutine in Perl
You can return a value from Perl subroutine as you do in any other programming language. If you are not returning a value from a subroutine then whatever calculation is last performed in a subroutine is automatically also the return value.You can return arrays and hashes from the subroutine like any scalar but returning more than one array or hash normally causes them to lose their separate identities. So we will use references ( explained in the next chapter ) to return an array or hash from a function.ExampleLet's try the following example, which takes a list of numbers and ...
Read MorePrivate Variables in a Subroutine in Perl
By default, all variables in Perl are global variables, which means they can be accessed from anywhere in the program. But you can create private variables called lexical variables at any time with the my operator.The my operator confines a variable to a particular region of code in which it can be used and accessed. Outside that region, this variable cannot be used or accessed. This region is called its scope. Lexical scope is usually a block of code with a set of braces around it, such as those defining the body of the subroutine or those marking the code ...
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