Perl examples

1) A perl program to read a line  from standard input and  output each words entered using foreach.

#!/usr/bin/perl

$str1 = <STDIN>;

chomp $str1;

$count =1;

foreach $chr1 (split( //,$str1)){

print "\n word $count = $chr1";

$count++;

}

2)  A perl Program to reverse an entered  input of line.

a) Reverse the line of string as a whole.

b) reverse each words in the line

#!/usr/bin/perl

print "\n enter string";

$var1 = <STDIN>;

print "\n enter string";

$var2 = <STDIN>;

$rev1 = reverse($var1);

$rev2 = join ( " ",reverse split(" ",$var2));

print "\n reverse of $var1 = $rev1";

print "\n reverse of $var2 = $rev2";


3)   Perl program containing   substitution of expressions containing variables within patterns.

#!/usr/bin/perl

$no = 25;

$str1 = 'MY NUM IS $no';

$str2 = 'MY NUM INTO 2 IS $no';

$str1  =~ s/\$([a-z]+)/${$1}/g;

$str2  =~ s/\$([a-z]+)/${$1} * 2/eg;

print "\n $str1";

print "\n $str2";


4)Perl program to check whether input number is a natural number or integer.

#!/usr/bin/perl

$str = <STDIN>;

if ( $str =~ /^\d+$/ || $str =~ /^[0-9]+$/)

{

print "\nnatural number";

}

elsif ( $str =~ /^[+-]?\d+$/ || $str =~ /^-?\d+$/)

{

print "\nInteger";

}

else

{

print "\nnot an integer"

}



5)Perl program to add or subtract days from an entered date in YYYY-MM-DD format.It requires the Date::calc module.

#!/usr/bin/perl

use Date::Calc qw(Add_Delta_Days);

print "\nenter date in YYYY-MM-DD  ";

$dt = <STDIN>;

print "\nEnter days to add or -days to subtract  ";

$of = <STDIN>;

@darr = split("-",$dt);

$yr  = $darr[0];

$mon = $darr[1];

$ddi = $darr[2];

printf( "\nnew date  = %04d-%02d-%02d",Add_Delta_Days($yr,$mon,$ddi,$of) );


6) A perl program to print no of days, hours, minutes & seconds between two given  days

#!/usr/bin/perl

use Date::Calc qw(Delta_Days Delta_DHMS);

@date1 = (2004,03,13);

@date2 = (2003,12,15);

$ddiff = Delta_Days(@date2,@date1);

print "\n The days between the two dates $ddiff";

@dtim1 = (2005,06,17,14,36,17);

@dtim2 = (2005,06,18,11,19,35);

@dtimdiff = Delta_DHMS(@dtim1,@dtim2);

print "\n $dtimdiff[0] days $dtimdiff[1] Hrs $dtimdiff[2] Mins $dtimdiff[3] Secs";

.


7) A Perl program to add  a specified days,hours,minutes,secinds to a given date and time.

#!/usr/bin/perl

use Date::Calc qw(Add_Delta_DHMS);

print "\nenter Date & Time in YYYY-MM-DD-HH-MI-SS  ";

$dt = <STDIN>;

print "\nEnter duration to add in DAYS,HRS,MIN,SS   ";

$of = <STDIN>;

@dtmarr = split("-",$dt);

$yr  = $dtmarr[0];

$mon = $dtmarr[1];

$ddi = $dtmarr[2];

$hh = $dtmarr[3];

$mi = $dtmarr[4];

$ss = $dtmarr[5];

@durarr = split(",",$of);

$days = $durarr[0];

$hrs = $durarr[1];

$mins = $durarr[2];

$secs = $durarr[3];

printf( "\nnew date  = %04d-%02d-%02d %02d:%02d:%02d",Add_Delta_DHMS($yr,$mon,$ddi,$hh,$mi,$ss,$days,$hrs,$mins,$secs) );


8) A perl program to read a paragraph into an array and then print a particular line.

#!/usr/bin/perl

@para = (<<"INPUT" =~ m/^\s*(.+)/gm);

It was a day, long and hectic,

the day which I slogged more than ever

but got no reward and no accolades.

INPUT

print "\n $para[1]";


9) A perl program showing different ways of  storing variables in array.

#!/usr/bin/perl

@arr1 = "what are you doing";            #strores entire string as one element;

@arr2 = ("what","are","You","doing");   # stores quoted strings as individual elements

@arr3 = qw (what are you doing ?);         # stores individual words as elements

print "\n $arr1[0]";

print "\n $arr1[2]";

print "\n $arr2[2]";

print "\n $arr3[2]";

10)A perl progrm to store output of Unix ls command into an array.
#!/usr/bin/perl

@arr1 = qx(ls);

print "$arr1[0],$arr1[1],$arr1[2]";

11) A perl program to reduce the  length of an array using $#ARRAY.

#!/usr/bin/perl
@vararr = qw(This is an array);

$x = $#vararr;
print "\n|@vararr| length = " . ($x + 1);
$#vararr -= 1;
$x = $#vararr;
print "\n |@vararr| - length = " . ($x + 1);