探索Perl语言：入门学习与实战指南

brew install perl

sudo apt-get install perl    # Debian/Ubuntu
sudo yum install perl        # CentOS/RHEL

cpan

# 标量变量示例
my $name = "John";
my $age = 30;
my $pi = 3.14159;

print "Name: $name\n";
print "Age: $age\n";
print "Pi: $pi\n";

# 数组示例
my @fruits = ("apple", "banana", "cherry");
print "First fruit: $fruits[0]\n";

# 添加元素
push(@fruits, "date");
print "All fruits: @fruits\n";

# 哈希示例
my %age = ("John" => 30, "Jane" => 28, "Jim" => 35);
print "John's age: $age{'John'}\n";

# 添加键值对
$age{'Jack'} = 40;
print "All ages: ";
foreach my $key (keys %age) {
    print "$key: $age{$key} ";
}
print "\n";

# 条件语句示例
my $number = 10;

if ($number > 20) {
    print "Number is greater than 20\n";
} elsif ($number == 10) {
    print "Number is 10\n";
} else {
    print "Number is less than or equal to 20\n";
}

# while循环示例
my $count = 1;
while ($count <= 5) {
    print "Count: $count\n";
    $count++;
}

# for循环示例
for (my $i = 0; $i < 5; $i++) {
    print "Iteration: $i\n";
}

# foreach循环示例
my @colors = ("red", "green", "blue");
foreach my $color (@colors) {
    print "Color: $color\n";
}

# 子程序示例
sub greet {
    my ($name) = @_;
    print "Hello, $name!\n";
}

greet("John");
greet("Jane");

# 模块示例
package MyModule;

sub hello {
    print "Hello from MyModule!\n";
}

1; # 模块文件以1结尾，表示成功加载

use MyModule;
MyModule::hello();

# 文件读取示例
open(my $fh, '<', 'input.txt') or die "Cannot open file: $!";
while (my $line = <$fh>) {
    print $line;
}
close($fh);

# 文件写入示例
open(my $fh, '>', 'output.txt') or die "Cannot open file: $!";
print $fh "This is a test.\n";
close($fh);

# 正则表达式示例
my $text = "The quick brown fox jumps over the lazy dog";

# 匹配单词
if ($text =~ /fox/) {
    print "Found 'fox' in the text.\n";
}

# 替换单词
$text =~ s/dog/cat/;
print "Updated text: $text\n";

# DBI模块示例
use DBI;

my $dbh = DBI->connect("DBI:mysql:database=testdb;host=localhost", "username", "password", {'RaiseError' => 1});

my $sth = $dbh->prepare("SELECT * FROM users");
$sth->execute();

while (my $row = $sth->fetchrow_hashref()) {
    print "User: $row->{name}, Age: $row->{age}\n";
}

$sth->finish();
$dbh->disconnect();

# LWP模块示例
use LWP::Simple;

my $url = 'http://example.com';
my $content = get($url);
die "Couldn't get $url" unless defined $content;

print "Content from $url:\n$content\n";

# JSON模块示例
use JSON;

my $json_text = '{"name": "John", "age": 30}';
my $data = decode_json($json_text);

print "Name: $data->{name}, Age: $data->{age}\n";

my $new_json_text = encode_json({name => "Jane", age => 28});
print "JSON: $new_json_text\n";

use LWP::UserAgent;
use HTML::TreeBuilder;

my $url = 'http://example.com';
my $ua = LWP::UserAgent->new;
my $response = $ua->get($url);

if ($response->is_success) {
    my $content = $response->decoded_content;
    my $tree = HTML::TreeBuilder->new_from_content($content);

    foreach my $link ($tree->look_down(_tag => 'a')) {
        my $href = $link->attr('href');
        print "Link: $href\n" if defined $href;
    }

    $tree->delete;
} else {
    die "Failed to fetch $url: ", $response->status_line;
}

use DBI;

my $dbh = DBI->connect("DBI:mysql:database=testdb;host=localhost", "username", "password", {'RaiseError' => 1});

my $sth = $dbh->prepare("INSERT INTO users (name, age) VALUES (?, ?)");
$sth->execute("John", 30);
$sth->execute("Jane", 28);

$sth = $dbh->prepare("SELECT * FROM users");
$sth->execute();

while (my $row = $sth->fetchrow_hashref()) {
    print "User: $row->{name}, Age: $row->{age}\n";
}

$sth->finish();
$dbh->disconnect();

use Test::More tests => 3;

sub add {
    my ($a, $b) = @_;
    return $a + $b;
}

is(add(2, 3), 5, '2 + 3 = 5');
is(add(0, 0), 0, '0 + 0 = 0');
is(add(-1, 1), 0, '-1 + 1 = 0');

use LWP::UserAgent;
use JSON;
use Test::More tests => 2;

my $ua = LWP::UserAgent->new;
my $url = 'http://api.example.com/data';

# 测试GET请求
my $response = $ua->get($url);
is($response->code, 200, 'GET request should return 200 OK');

# 测试POST请求
$response = $ua->post($url, Content => encode_json({key => 'value'}));
is($response->code, 201, 'POST request should return 201 Created');