2. A statement block is a sequence of statements, enclosed in
matching curly braces. It looks like this:
{
first_statement;
second_statement;
third_statement;
...
last_statement; # last statement semicolon is optional.
}
3. print "how old are you? ";
$a = <STDIN>;
chomp($a);
if ($a < 18) {
print "So, you're not old enough to vote, eh?n";
} else {
print "Old enough! Cool! So go vote!n";
$voter++; # count the voters for later
}
4. print "how old are you? ";
$a = <STDIN>;
chomp($a);
unless ($a < 18) {
print "Old enough! Cool! So go vote!n";
$voter++;
5.
6.
7.
8. Arrays are a special type of variable that
store list style data types. Each object of the
list is termed an element and elements can
either be a string, a number, or any type of
scalar data including another variable.
Array variables have the same format as
scalar variables except that they are
prefixed by an @ symbol.
Arrays can also hold arrays.
9. array variable is a variable
which is a list of scalars (ie
numbers and strings). Array
variables have the same
format as scalar variables
except that they are
prefixed by an @ symbol.
@var =
(value1..valueN);
@var = (“str1”,”str2”)
($a, $b) = @alphabets;
# $a and $b are the
first two elements of
@alphabets array
#!/usr/bin/perl
main(@ARGV);
my $days =qw^Sun Mon
Tue Wed Thu Fri Sat^;
Print @days;
My $days=31;
Print $days;
# It is valid to use the same
name for scalars and array
types.
10. My @array1 =(1,2,3);
My @array2 = (@array1 ,4,5,6);
Print “@array2”; # prints 1 2 3 4 5 6
Print $array2[2]; # prints 3
Print scalar @array2
# Here the scalar will contain the value 6 , as
the total no’of elements in the array2 is
equal to 6
11. #!/usr/bin/perl
use warnings;
use strict;
say “input a number”;# functionality same as
“print” , adds a new line character at the end
My chomp($choice =<STDIN>);
print qw(BMW Ferrari McLaren Jaguar )
[$choice]);
OUTPUT:- McLaren
12. If you input a decimal value .. Choice = 1.2 then perl will
round if off and will output Ferrari.
If you input a negative number.. Choice = -1 then perl
starts counting backwards from the end of the list.
LIST Slices
instead of putting a scalar value [$choice].. We can also
print out multiple values in the list by putting a list of
index values
(20,30,99,15,22,13,56,76,34)[2,5,7]
This can also be used on strings.
13. What happens when you assign a array to a scalar?
@array1 = qw(a b c d);
$scalar1 = @array1;
Print “array cotents:” @array1 # prints with no spaces
Print “array contents: @array1” # prints with spaces
@array1 = (1,2,3,4,5)
Print @array1 “n”;
Print “@array1n”
$scalar1 = “@array1n”; is Same as $scalar = “1 2 3 4 5n”;
$scalar = @array1; is same as $scalar = 5 # as the total elements
in array is 5
14. (1 .. 10)
( -9 .. 9)
(a .. z)
Cant mix up the list of elements list .. (a .. 5) or (-1 .. B) etc.,
Always the right-hand element should be higher than the left-handed
element.
We can mix up the Slices and ranges.. For effective programming
@coins = qw(Quarter Dime Nickel Penny);
@slicecoins = @coins[0,2];
Say "@slicecoins"; # prints 0th
index value “Quarter” and 2nd
value “Nickel”
with Spaces b/w strings.
16. @lang = qw(java python perl c);
My $element;# declating scalar var for iteration
For $element (@lang)
{ print $element “n”;
}
For <iterator> (<list of array>) BLOCK
If we don’t supply an iterator of our own.. Perl supplies a
special variable S_ which is often used in perl functins as
default value
@array1 = (1,2,3,4);
Print “before @array1 n”
For (@array1) {$_ * = 10}
Print “after @array1n”
17. #!/usr/bin/perl
my @coins =
("Quarter","Dime","Nickel");
# ADD ELEMENTS
push(@coins, "Penny");
print "@coins";
print "<br />";
unshift(@coins, "Dollar");
print "@coins";
# REMOVE ELEMENTS
pop(@coins);
print "@coins";
shift(@coins);
Adding elements is a breeze, we
use the following functions to
add/remove and elements:
push() - adds an element to the
end of an array.
unshift() - adds an element to
the beginning of an array.
pop() - removes the last element
of an array.
shift() - removes the first
element of an array.