perl学习笔记 - 快速入门！

参考文档

[1].a brief introduction and overview of Perl

[2].Perl syntax
[3].Perl 5教程

[4].Perl programming documentation
[5].http://www.ibm.com/developerworks/cn/linux/theme/perl/index.html

 

代码整理：

数据类型：标量、数组、哈希

逻辑控制：if,while,until,for

-：subroutine,regular

~/test/perl$vim perlintro.pl

输入以下内容：

 

#!/usr/bin/perl
use strict;   #caught potential problems.
use warnings; #like command-line switch -w

print "*************Command-line************/n";
print "$0 @ARGV /n";

#
#Scalars
#
print "*************Scalars************/n";
my $animal = "camel";
my $answer = 42;

print "animal = ",  $animal ,"/n";
print "answer = ", $answer, "/n";

#
#Array
#
print "*************Array************/n";
my @animals = ("camel", "llama", "owl");
my @numbers = (23, 42, 69);
my @mixed = ("camel", 32, 1.25);

print "animals[0] = ", $animals[0], "/n";
print "animals[1] = ", $animals[1], "/n";

#
# hash
#
print "*************hash************/n";
my %fruit_color = (
    apple  => "red",
    banana => "yellow",
);
print 'fruit_color{"apple"} = ', $fruit_color{"apple"}, "/n";

my @fruits = keys %fruit_color;
my @colors = values %fruit_color;

print "*************foreach************/n";
foreach(@fruits) {
    print "This fruits element is $_/n";
}

#
# if
#
print "*************if************/n";
my $fruit = $fruits[1];

if ($fruit eq  "apple"){
    print "fruit == apple/n";
} elsif ($fruit eq "banana") {
    print "fruit == banana/n";
} else {
    print "not apple or banana/n";
}

# the traditional way
my $zippy=1;
if ($zippy) {
    print "Yow!/n;"
}

# the Perlish post-condition way
my $bananas=0;
print "Yow!/n" if $zippy;
print "We have no bananas/n" unless $bananas;

#
# while
#
print "*************while************/n";
print "/n";
my $count = 0;
while ($count < 10) {
    print "count = ", $count, "/n";
    $count += 1;
}

print "*************until************/n";
until ($count == 0) {
    print "count = ", $count, "/n";
    $count -= 1;
}

#
# for
#
print "*************for************/n";
my $max = 10;
my $i = 0;
for (; $i <= $max; $i++) {
    print "i = " , $i, "/n";
}

#
# file
#
print "*************file************/n";

print "***read data from file: input.dat***/n";
open(my $in, "<", "input.dat") or die "Can't open input.dat:$!/n";
while (<$in>) { print "$_";}
close $in or die "$in:$!/n";

print "***write data to file: output.dat***/n";
open(my $out, ">", "output.dat") or die "Can't open output.dat:$!/n";
$i = 0;
for (;$i < 10; $i++) { print $out $i,"/n";}
close $out or die "$out:$!/n";

print "***append data to file: my.log.***/n";
open(my $log, ">>", "my.log") or die "Can't open my.log:$!/n";
print $log "append file!!!!/n";
close $log or die "$log:$!/n";

#
# Regular expressions
#
print "****** Regular expressions ******/n";

# Simple matching
# operator : // , =~
print "***Simple matching***/n";
foreach(@fruits) {
    print "apple/n" if (/apple/);
}

if ($animal =~ /camel/) {print "animal is camel/n"; }

# Simple substitution
# operator : s///
print "*** Simple subsitution ***/n";
my $a = "hello aaa,aaa,aaa";
my $b = $a;
$b =~ s/aaa/bbb/;
my $c = $a;
$c =~ s/aaa/ccc/g;
print "a = $a , b = $b, c = $c/n";

my $email = '[e-mail]';
if ($email =~ /([^@]+)@(.+)/) {
    print "Username is $1/n";
    print "Hostname is $2/n";
}


#
# Writing subroutines
#
print "***************Writing subroutines******************/n";
sub logger {
    print 'in sub logger @_ = ', @_, "/n";
    my $logmessage = shift;
    open my $logfile, ">>", "my.log" or die "Could not open my.log: $!";
    print $logfile $logmessage;
}
logger("We have a logger subroutine!");

# return value
sub square {
    my $num = shift;
    my $result = $num * $num;
    return $result;
}

my $sq = square(8);
print "squere(8) = $sq/n";

 

 

执行脚本

~/test/perl$chmod +w perlintro.pl
~/test/perl$./perlintro.pl