#!/usr/bin/perl
#In order to make the code more robust ,to start every program with the following lines
use strict;
use warnings;
#basic syntax over
print "Hello , world/n";
print 'hello , world/n';
print 73;
print("/nhello , world/n");
#perl variable types
#Scalars
my $name = "renbing";
my $age = 22;
print "my name is $name,my age is $age./n";
#arrays
my @animals = ("camel", "llama", "owl");
my @numbers = (23,22,66);
my @mixed = ("camel", 43, 1.332);
print $animals[0];
#the special variable $#array tells you the index of the last element of an array;
#$#array +1 to tell you how many items there are in an array
print $mixed[$#mixed];
print "/n";
print @numbers[1,2];
print "/n";
print @numbers[0..$#numbers];
#hashes
#my %fruit_color = ("apple", "red", "banana", "yellow");
my %fruit_color = (
apple => "red",
banana => "yellow",
);
print "/n";
print $fruit_color{"apple"};
my @fruits = keys %fruit_color;
my @colors = values %fruit_color;
print "/n";
#key string comparison
# eq ne lt gt le ge
#file and i/o
open(my $in, "<", "input.txt") or die "can't open"
