#!usr/bin/perl -w
use strict;

##### Defining array of numbers
my@numbers = (1,2,3);
print "Array of numbers: @numbers\n\n";

##### Defining array of strings
my@animals = ("cat", "dog", "bird");
print "Array of strings: @animals\n\n";

##### quoted words is a shorthand way to create an array of strings without using quotes
@animals = qw(cat dog bird);
print "Without quotes: @animals\n\n";

##### Print the first element of the array animals
##### Elements of arrays are indexed starting with the value 0
print "First element of array \@animals: $animals[0]\n\n";

##### $# in front of the name of an array returns the last index value of an array
##### This value is one less than number of elements in the array since the first index value is 0
print "Last index value: $#animals\n\n";

##### scalar returns the number of elements in an array
print "Number of elements: ";
print scalar(@animals), "\n\n";

##### Negative values reference elements in the array starting from the last position
print "Last element of array: $animals[-1]\n\n";

##### Create array of numbers incrementing by 1
@numbers = (1..5);
print "Counting up by 1: @numbers\n\n";

##### Reverse the order of an array
##### One way to generate an array of decreasing numbers
my@num_rev = reverse(@numbers);
print "Reversed array: @num_rev\n\n";

##### Pop removes the last element from an array
##### This value can be assigned to a different variable if you want to keep it
my$var1 = pop(@numbers);
print "Popped variable: $var1\n\n";
print "Remaining values in array: @numbers\n\n";

##### Push adds a new element onto the end of an array
push(@numbers, 8);
print "Array after push: @numbers\n\n";

##### Shift removes the first element from an array
##### Here it is not being stored
shift(@numbers);
print "Array after shifting: @numbers\n\n";

##### Unshift adds a new element to the front of an array 
unshift(@numbers, 10);
print "Array after unshift: @numbers\n\n";


##### Sorting values in array 
##### Use $a <=> $b to compare values
##### Use $a cmp $b for strings
my@sorted = sort {$a <=> $b} (@numbers);
print "Sorted array: @sorted\n\n";

##### Sorting the array numbers by ASCII value
##### Since all numbers in the array are not two digit, 10 is sorted before 2 since 1 is less than 2
##### For 2 to be sorted before 10 using this format, 2 would have to be written as 02
my@sorted2 = sort(@numbers);
print "Sorted by ASCII: @sorted2\n\n";

##### Creating string of characters
my$char = "alksjdflkaskjlfd";
print "Random string: ";
print $char, "\n\n";

##### Creating array of characters from a string by splitting between each character
my@chars = split(//,$char);
print "After split: @chars\n\n";

##### Splitting a string by the character 'a'
##### This removes 'a' and generates an array
##### A string can be split by any character or regular expression you want such as a comma or a tab
##### In this 'a' is the first character in the string so a null value is generated at index position 0
my@chars2 = split(/a/,$char);
print "Split by 'a': @chars2\n\n";

##### The foreach loop steps through a list of values executing the function in the loop for each value
##### This loop will print each element of the array chars2
##### Here the variable $var130 is used as a control variable. It takes on a new value for each iteration
foreach my $var130 (@chars2) {
   print "HELLO >>$var130<<\n";
}
print "\n";

print "Max Index:", $#chars2, "\tNumber of Elements:", scalar(@chars2), "\n";
##### FOR LOOP #1
##### This for loop performs the same function as the foreach loop used previously - printing each element of the array chars2
##### The for loop differs because it requires 3 components:
##### 1) my $count=0 initializes the expression
##### 2) $count < scalar(@chars2) is the test expression.  As long as this expression is true, the code will continue to be executed
##### 3) $count++ resets the initial expression each time the loop is executed
##### $count is being used to define the index value of the @chars2 array
for (my $count=0; $count < scalar(@chars2); $count++) {
   print "HI1 :$count>", $chars2[$count], "<:\n";
}
print "\n";

##### FOR LOOP #2
##### In this for loop, the initial position is the last index position of the chars2 array and the loop counts down to the first index position
for (my $count=$#chars2; $count >= 0 ; $count--) {
   print "Hello :$count>", $chars2[$count], "<:\n";
}
print "\n";

##### FOR LOOP #3
##### This for loop does the same thing as FOR LOOP #1. However, the test expression is defined by the last index position rather than the number of elements in the array.
for (my $count=0; $count <= $#chars2; $count++) {
   print "HI2 :$count>", $chars2[$count], "<:\n";
}
print "\n";

##### The join function allows you to combine all elements of an array into one string
print "After join: ";
print join(",", @chars2), "\n\n";

##### Defining two dimensional array
my @Dim2 = ([1,2,3], [4,5,6], [7,8,9]);

##### Using a foreach loop to go through each row of the 2D array and print out the row
foreach my $row (@Dim2) {
    print "BAD CONSTRUCTION: $row\n";


    #Equivalent methods to print the row
    print "PERL ARRAY PRINT:", "@$row\n";
    print "JOIN PRINT      :", join (" ", @$row), "\n";
    print "JOIN TAB        :", join ("\t", @$row), "\n";



    foreach my $col (@$row) {
           print "Element = $col\t";
    }
    print "\n\n";
}