perl学习

#!/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"