Guide

1. 安装及运行

下载
1. 方式一: scoop install main/perl@5.32.1.1
2. 方式二: https://www.perl.org/get.html
测试
1. perl -v
运行方式
1. perl -we <perl code>(-e, execute)
2. perl -w script.pl(-w, warning)

2. 基础语法

2.1. 注释

单行注释: #
多行注释: 以=pod开头, =cut结尾

# 单行注释
=pod 多行注释
print "Hello World!\n";
print "Hello World!\n";
print "Hello World!\n";
print "Hellod World!\n";
=cut

2.2. 单, 双引号

''单引号: 解析
""双引号: 不解析

print "Hello\n"; # 双引号
print 'Hello\n'; # 单引号

2.3. Here 文档

格式

$var = << FLAG;
...
FLAG

示例

$str1 = << "eof";
this is a note \n
haha ha .
eof
print $str1;

$str2 = << 'eof';
this is a note \n
haha ha .
eof
print $str2;

2.4. 转义字符

\n

$str = "http:// \\  \n";
print $str;

$str = "http:// \\\\  \n";
print $str;

3. 数据类型

3.1. 标量

$var = 1;

# 标量
$num = 12; # 数字
$str = "12"; # 字符串

3.2. 数组

@array = (1, 2);

# 数组
@array = (1,2,3);
print @array;
print "\n";
print "$array[0] $array[1] $array[2]";
print "\n";

3.3. 哈希

%hash = ('a' => 1, 'b' => 2);

# 哈希
%hash = (
    'a' => 1,
    'b' => 2,
);
print %hash;
print "\n";
print "$hash{'a'}";
print "\n";

3.4. 整型

$x = 1

# 整型
$x = 12;
if ($x + 1 == 13) {
    print "$x + 1 == 13 \n";
}
$x = 011;
print "$x = 011 \n";
$x = 0x11;
print "$x = 0x11 \n";

3.5. 浮点型

$x = 1.0

# 浮点数
$x1 = 0.1;
$x2 = -0.2;
$x3 = 1.1e3;
$x4 = -1.1e4;
print "$x1 $x2 $x3 $x4 \n";

3.6. 字符串

$x = '1'

# 字符串
$v1 = "字符串";
$v2 = '字符串2';
print "$v1 \n $v2 \n";

3.7. 转义字符

转义字符	含义
\	反斜线
\'	单引号
\"	双引号
\a	系统响铃
\b	退格
\f	换页符
\n	换行
\r	回车
\t	水平制表符
\v	垂直制表符
\0nn	创建八进制格式的数字
\xnn	创建十六进制格式的数字
\cX	控制字符, X可以是任何字符
\u	强制下一个字符为大写
\l	强制下一个字符为小写
\U	强制将所有字符转换为大写
\L	强制将所有字符转换为小写
\Q	将到\E为止的非单词字符加上反斜线
\E	结束\L, \U, \Q

4. 变量

不同变量可使用相同的变量
不需要显示声明
数组
- @var
- $var[index]
哈希
- %var
- $var{'key'}

# 数组
@ages = (23, 24, 25);
print "$ages[0], $ages[1], $ages[2] \n";

# 哈希
%names = (
    'a' => "var: a",
    'b' => "var: b",
    'c' => "var: c",
);
print "$names{'a'}, $names{'b'}, $names{'c'} \n";

# 复制数组
@copy = @ages;
print "@ages \n";
print "@copy \n";

# 数组个数
$size = @ages;
print "$size \n";

5. 标量

5.1. 字符串连接

$str3 = $str1 . $str2

# 字符串连接
$str1 = "hello";
$str2 = "world";
$str3 = $str1.$str2;
$str4 = $str3 . 3;
print "$str3 \n";
print "$str4 \n";
print "hello"."world"."\n";

5.2. 数字运算

$sum = $x + $y

# 数字运算
$n1 = 1;
$n2 = 2;
$n3 = $n1 + $n2;
print "$n3 \n";

5.3. 打印多行字符串

# 多行字符串
print << "eof";
line 1, ..  ..
line2 , .. ??
eof
print "LF";

5.4. 特殊字符

__FILE__ __LINE__ __PACKAGE__

# 特殊字符
print "File name: " . __FILE__ . "\n";
print "Line number: " . __LINE__ . "\n";
print "Package name: " . __PACKAGE__ . "\n";
print "__FILE__ __LINE__ __PACKAGE__\n"; # unable to parse

5.5. ASCII字符

$gendloop = v103.101.110.100.108.111.111.112;

# ASCII字符
# 48(0), 65(A), 97(a)
$str1 = v102.111.111.108;
$str2 = v103.101.110.100.108.111.111.112;
print "$str1 \n";
print "$str2 \n";

6. 数组

6.1. 创建数组

@array = (1, 2, 3);

# 创建
@array1 = (1, 2, "s");
print @array1;
print "\n";

@array2 = qw/2 3 "ss"/;
print @array2;
print "\n";

@array3 = qw/
1
2
3
/;
print @array3;
print "\n";

$array4[0] = 'Monday';
$array4[6] = 'Sunday';
print @array4;
print "\n";
print "$array4[0] $array4[1] $array4[6]";
print "\n";
$size = @array4;
print $size;
print "\n";

6.2. 访问数组元素

$array[index]

# 访问数组元素
@sites = qw/abc def ghi/;
print "$sites[0]\n";
print "$sites[2]\n";
print "$sites[-1]\n";

6.3. 数组序列号

@seq = (1..10);

# 数组序列号
@seq1 = (1..10);
print "@seq1\n";

@seq2 = (-3..3);
print "@seq2\n";

@seq3 = ('a'..'z');
print "@seq3\n";

@seq4 = ('A' .. 'Z');
print "@seq4\n";

@seq5 = ('a' .. 'Z');
print "@seq5\n";

@seq6 = ('A' .. 'z');
print "@seq6\n";

6.4. 数组大小

$size = @array

# 数组大小
@array5 = (1,2,3);
print "size: ", scalar @array5, "\n";

$array5[10] = 10;
$size = @array5;
$max_index = $#array5;
print "real size: 4 \n";
print "size: $size \n";
print "max index: $max_index \n";

6.5. 添加和删除元素

$size = push(@array, new_end_element);

$end_element = pop(@array);

$size = unshift(@array, new_begin_element);

$begin_element = shift(@array);

# 添加和删除数组元素
@seq7 = (1..4);
$size = @seq7;
print "original: \@seq7 = @seq7\n"."size: $size \n";

# add one at the end
$size = push(@seq7, 100);
print "push: \@seq7 = @seq7\n"."size: $size \n";

# delete the end
$var = pop(@seq7);
print "pop: \@seq7 = @seq7\n" . "var: $var \n";

# add one at the begin
$size = unshift(@seq7, "23");
print "unshift: \@seq7 = @seq7\n" . "size: $size \n";

# delete the begin
$var = shift(@seq7);
print "shift: \@seq7 = @seq7\n" . "var: $var \n";

6.6. 切割数组

@sub = @array[3..5];

# 切割数组
@seq8 = (1..9);
@seq8_sub = @seq8[3..5];
print "@seq8\n";
print "@seq8_sub\n";

6.7. 替换元素

@new_array = splice(@array, offset, length, @to_replace);

# 替换元素
# splice (@array, offset, length, list)
@seq9 = (1..9);
print "@seq9\n";
@seq9_2 = splice(@seq9, 3, 3, (0,0,0));
print "@seq9_2\n";
print "@seq9\n";

6.8. 字符串转数组

@array = split(separator, $str);

# 将字符串转换为数组
# split (separator, $string [, number])
$str1 = "1 2 3";
@str1_array = split(' ', $str1);
$size = @str1_array;
print "@str1_array\n" . "size: $size\n";

$str2 = "1-2-3";
@str2_array = split('-', $str2);
$size = @str2_array;
print "@str2_array\n" . "size: $size\n";

$str3 = "1-2-3";
@str3_array = split('-', $str3, 2);
$size = @str3_array;
print "@str3_array\n" . "size: $size\n";

6.9. 数组转字符串

$str = join(connector, @array);

# 将数组转换为字符串
# join (connect, @array)
@array = (1..5);
$str = join(' -> ', @array);
print "$str\n";

6.10. 数组排序

@sorted_array = sort(@array);

# 数组排序
# sort (@array)
# sort by ASCII
@array = ('b', 'c', 'a', 'e', 'd');
@sort1 = sort(@array);
print "@sort1\n";

6.11. 合并数组

@array3 = (@array1, @array2);

# 合并数组
@numbers = (1, 3, (4,5,6));
print "@numbers\n";

@nums2 = (1,3,5);
@nums3 = (2,4,6);
@nums4 = (@nums2, @nums3);
print "@nums4\n";

6.12. 从列表中选择元素

$var = @array[index];

# 从列表中选择元素
@list = (1..5);
$var = $list[2];
$var2 = (1..5)[2];
print "$var\n$var2\n";

7. 哈希

格式: %var

7.1. 创建哈希

%hash = ('a' => 'A', 'b' => 'B');

# 1. 创建哈希
# method 1
%h1 = ('Person1', 'Maria', 'Person2', 'Jane');
print %h1, "\n";
print $h1{'Person2'}, "\n";

# method 2
$data{'P1'} = 'You';
$data{'P2'} = 'Me';
print %data, "\n";

# method 3
%data = (
    'g: ' => 'google',
    'bd: ' => 'baidu'
);
print %data, "\n";

7.2. 访问哈希元素

单个: $value = $hash{key}

多个(数组): $values = @hash{'key1', 'key2'}

# 2. 访问哈希元素
# 单个
print "$data{'g'}", "\n";
print "$data{'bd'}", "\n";
# 多个
@array = @data{'g', 'bd'};
print @array, "\n";

7.3. 读取哈希的 key 和 value

keys(%hash) values(%hash)

# 3. 读取哈希的 key 和 value
%data = (
    'a' => 1,
    'b' => 2
);
print %data, "\n";

# keys
@names = keys(%data);
print @names, "\n";

# values
@nums = values(%data);
print @nums, "\n";

7.4. 检测元素是否存在

exist($hash{key})

# 4. 检测元素是否存在
%data = (
 'a' => 'apple',
    'b' => 'banana',
    'c' => 'Exist C'
);
if(exists($data{'c'})) {
 print("$data{'c'}, "\n");
}
else {
 print("doesn't exist", "\n");
}

7.5. 获取哈希大小

@keys = keys(%hash); $size = @keys;

# 5. 获取哈希大小
$data = (
 'a' => 'A',
 'b' => 'B',
 'c' => 'C',
);
@keys = keys(%data);
$size = @keys;
print("$size", "\n");

7.6. 添加或删除元素

$hash{'new_key'} = 'new_value';

$del_value = delete($hash{'del_key'});

# 6. 添加或删除元素
%data = (
 'a' = 'A',
 'b' = 'B',
 'c' = 'C',
);
print(%data, "\n");
$data{'d'} = 'D';
print(%data, "\n");
if(exist($data{'a'})) {
 $del_value = delete($data{'a'});
    print("\$ret = $ret\n");
}
print(%data, "\n");

7.7. 迭代哈希

foreach $key (keys(%hash))

while(($key, $value) = each(%hash))

%data = (
    'a' => 'A',
    'b' => 'B',
    'c' => 'C'
);
foreach $key (keys(%data)) {
 print("$key\n");
}
while(($key, $value) = each(%data)) {
 print("$data{$key}\n");
}

8. 条件语句

8.1. true 和 false

false: 0 '0' "0" () undef

true: 其他

# true 和 false
if(0) { print(0 . " is " . "true", "\n"); }
else { print(0 . " is " . "false", "\n"); }

if('0') { print('\'0\'' . " is " . "true", "\n"); }
else { print('\'0\'' . " is " . "false", "\n"); }

if("0") { print('"0"' . " is " . "true", "\n"); }
else { print('"0"' . " is " . "false", "\n"); }

@a = ();
if($a) { print('@()' . " is " . "true", "\n"); }
else { print('@()' . " is " . "false", "\n"); }

%a = ();
if($a) { print('%()' . " is " . "true", "\n"); }
else { print('%()' . " is " . "false", "\n"); }

if(undef) { print('undef' . " is " . "true", "\n"); }
else { print('undef' . " is " . "false", "\n"); }

if(!undef) { print('!undef' . " is " . "true", "\n"); }
else { print('!undef' . " is " . "false", "\n"); }

if('undef') { print('\'undef\'' . " is " . "true", "\n"); }
else { print('\'undef\'' . " is " . "false", "\n"); }

if("undef") { print('"undef"' . " is " . "true", "\n"); }
else { print('"undef"' . " is " . "false", "\n"); }

8.2. 条件语句 if

if(<true expr>)
if...else...
if...elsif...else...

# 条件语句
# if
if(1) {
    print('if', "\n");
}

# if.. else...
if(0) {
    print('if', "\n");
}
else {
    print('if else', "\n");
}

# if...elsif...else...
if(0) {
    print('if', "\n");
}
elsif(1) {
    print('if...elsif...else...', "\n");
}
else {
    print('else', "\n");
}

8.3. 条件语句 unless

unless(<false expr>)
unless...else...
unless...elsif...else...

# unless
@array = ();
unless(@array) {
    if(!$array[-1]) {
        push(@array, 'false will be executed');
    }
    else{
        push(@array, $array[-1]+1);
    }
}
print(@array, "\n");

# unless...else...
unless(1) {
    print("false", "\n");
}
else{
    print("true", "\n");
}

# unless...elsif...else
$a = 0;
unless($a < 1) {
    print("false to execute", "\n");
}
elsif($a < 2) {
    print("true to execute", "\n");
}
else{
    print('others', "\n");
}

8.4. 条件语句

switch
需安装
- cpan
- install Switch
使用要求
- 代码前加上use Switch;

# switch
=pod 需要安装Switch.pm模块
cpan
install Switch
=cut
use Switch;
$var = 10;
@array = (10, 20, 30);
%hash = ('key1' => 10, 'key2' => 20);
switch(1) {
    case 1            { print "数字 1"; next } # next 继续向下执行
    case "a"          { print "字符串 a" }
    case [1..10,42]   { print "数字在列表中"; next }
    case [1..10,42]   { print "数字在列表中";  }
    case (\@array)    { print "数字在数组中" }
    case /\w+/        { print "正则匹配模式" }
    case qr/\w+/      { print "正则匹配模式" }
    case (\%hash)     { print "哈希" }
    case (\&sub)      { print "子进程" }
    else              { print "不匹配之前的条件" }
}
print("\n");

8.5. 三元运算符

<expr> ? <true expr> : <false expr>

# 三元运算符
$ret = "Name" == "gendloop" ? "gendloop" : "guest";
print("$ret\n");

9. 循环

9.1. while

while(<true expr>)

# while
$a = 1;
while($a < 4) {
    print("$a", "\n");
    $a = $a + 1;
}
print("\n");

9.2. until

until(<false expr>)

# until
$a = 4;
until($a < 1) {
    print("$a", "\n");
    $a = $a - 1;
}
print("\n");

9.3. for

for(init; <true expr>; increment)

1; # for
for($a = 0; $a < 3; $a = $a + 1) {
    print($a, "\n");
}
print("\n");

9.4. foreach

foreach $var ($list)

# foreach
@array = (6..9);
foreach $e (@array) {
 print($e, "\n");
}
print("\n");

%hash = (
 'a' => 1,
    'b' => 2
);
foreach $e (keys(%hash)) {
 print($e, "\n");
}
print("\n");

9.5. do...while

do { ... } while(<true expr>);

# do...while
@a = (0..2);
do {
 $size = @a;
    $size = push(@a, $size);
    print("size = $size, \@a = ", @a, "\n");
}while($size < 6);
print("\n");

9.6. next

停止执行从next语句的下一语句开始到循环体结束标识符之间的语句，转去执行continue语句块，然后再返回到循环体的起始处开始执行下一次循环

next

next LABEL

# next
@array1 = (1..5);
foreach $a1 (@array1) {
 if($a1 == 3) {
        next;
    }
    print("$a1");
}
print("\n");
print("\n");

@array2 = ('a'..'e');
OUTER: foreach $a1 (@array1) {
 print("$a1: ");
    INNER: foreach $a2 (@array2) {
        if($a1 == 2) {
         print("\n");
            next OUTER;
        }
        elsif($a1 == 4 && $a2 eq 'c') {
            next INNER;
        }
        print("$a2");
    }
    print("\n");
}
print("\n");

9.7. last

退出循环语句块，从而结束循环，last语句之后的语句不再执行，continue语句块也不再执行

相当于break

# last
for($i = 1; $i < 5; ++$i) {
 if($i == 3) {
        last;
    }
    print($i);
}
print("\n");
print("\n");

9.8. continue

在条件语句再次判断前执行

只能用于 while 和 foreach 循环中

# continue
$i = 1;
while($i < 5) {
    $i++;
}continue{
    print("$i ");
}
print("\n");

foreach $e ((1..5)) {

}continue{
    print("$e ");
}
print("\n");
print("\n");

9.9. redo

直接转到循环体的第一行开始重复执行本次循环，redo语句之后的语句不再执行，continue语句块也不再执行。

redo

redo LABEL

# redo
$i = 1;
while($i < 5) {
    if($i == 3) {
        $i++;
        redo;
    }
    $i++;
}continue{
    print("$i ");
}
print("\n");

foreach $e ((1..5)) {
    if($e == 4) {
        $e  = $e + 100;
        redo;
    }
}continue{
    print("$e ");
}
print("\n");
print("\n");

9.10. goto

允许您将程序的执行跳转到指定的标签处

goto LABEL

goto <expr>

goto &NAME 把正在运行着的子进程替换为一个已命名子进程的调用

应尽量避免使用 goto

# goto
# goto LABEL
$a = 1;
LOOP: do {
    if($a == 3) {
        $a = $a + 1;
        print('break', "\n");
        goto LOOP;
        print('won\'t be execute', "\n");
    }
    print("\$a = $a", "\n");
    $a = $a + 1;
}while($a < 8);
print("\n");

# goto <expr>
$a = 1;
LOOP2: do {
    if($a == 3) {
        $a = $a + 1;
        goto 'LOOP' . '2';
        print('won\'t be execute', "\n");
    }
    print("\$a = $a", "\n");
    $a = $a + 1;
}while($a < 8);
print("\n");

10. 运算符

10.1. 算术运算符

+ - * / % **

# 算术运算符
$a = 2;
$b = 4;
print("$a + $b = ", $a+$b, "\n");
print("$a - $b = ", $a-$b, "\n");
print("$a * $b = ", $a*$b, "\n");
print("$a / $b = ", $a/$b, "\n");
print("$a % $b = ", $a%$b, "\n");
print("$a ** $b = ", $a**$b, "\n");

10.2. 比较运算符

== != <=> > < >= <=

字符串: eq ne cmp gt lt ge le

# 比较运算符
$a = 2;
$b = 4;
print("\"$a == $b\" => ", ($a == $b ? "true" : "false"), "\n");
print("\"$a != $b\" => ", ($a != $b ? "true" : "false"), "\n");
print("\"2 <=> 4\" => ", 2 <=> 4 , "\n");
print("\"3 <=> 3\" => ", 3 <=> 3 , "\n");
print("\"4 <=> 2\" => ", 4 <=> 2 , "\n");
print("\"$a > $b\" => ", ($a > $b ? "true" : "false"), "\n");
print("\"$a < $b\" => ", ($a < $b ? "true" : "false"), "\n");
print("\"$a >= $b\" => ", ($a >= $b ? "true" : "false"), "\n");
print("\"$a <= $b\" => ", ($a <= $b ? "true" : "false"), "\n");

10.3. 赋值运算符

= += -= *= /= %= **=

# 赋值运算符
$a = 2;
$b = 4;
$c = $a + $b;
print($c, "\n");
$c += $a;
print($c, "\n");
$c -= $a;
print($c, "\n");
$c *= $a + $b;
print($c, "\n");
$c /= $a + $b;
print($c, "\n");
$c %= 5;
print($c, "\n");
$c **= 100;
print($c, "\n");

10.4. 位运算

& | ^ ~ << >>

# 位运算
$x = 5;
$y = 6;
$x = $x ^ $y;
$y = $x ^ $y;
$x = $x ^ $y;
print($x . " " . "$y", "\n");

{
    $x = 8;
    $y = ~$x;
    print("$y", "\n");
}

{
    use integer;
    $x = 8;
    $y = ~$x;
    print("$y", "\n");
}

print(1 << 3, " ", 8 >> 1, "\n");

10.5. 逻辑运算符

and && or || not !

print(((1 < 2) and (2 < 3)) ? "true" : "false", "\n");
print(((1 < 2) && (2 < 3)) ? "true" : "false", "\n");

print(((1 < 2) or (2 > 3)) ? "true" : "false", "\n");
print(((1 < 2) || (2 > 3)) ? "true" : "false", "\n");

print(not(1 > 2) ? "true" : "false", "\n");

10.6. 引号运算符

q{} 为字符串添加单引号
qq{} 为字符串添加双引号

$a = 10;
$b = q{ a = $a };
print($b, "\n");
$b = qq{ a = $a };
print($b, "\n");

10.7. 其他运算符

. 连接两个字符串
x 对字符串重复指定次数
.. 序列范围
++, --
-> 类似指针作用, 用于引用

# 其他运算符
# .
$a = "a";
$b = "b";
print($a . $b, "\n");

# x
$c = ('acxb ' x 2);
print($c, "\n");

# ..
@a = (1..5);
@b = ('a'..'f');
print(@a, "\n");
print(@b, "\n");

# ++, --
$a = 3;
print($a++, "\n");
print(++$a, "\n");
print($a--, "\n");
print(--$a, "\n");

# ->
$a = ['a'..'f'];
$c = $a->[2];
print($a, "\n");
print($c, "\n");

11. 时间和日期

12. 子程序(函数)

12.1. 定义和调用

# 定义和调用
sub hello {
    print("Subroutine", "\n");
}

hello();

12.2. 传参

@_ 子程序参数
$_[i] 子程序第$i$个参数
传入的是引用

# 传参
sub average {
    $sum = 0;
    $count = 0;

    foreach $e (@_) {
        $sum += $e;
        $count++;
    }

    $mean = $sum / $count;

    print("@_", "\n");
    print("$_[0]", "\n");
    print("$_[-1]", "\n");
    print("$mean", "\n");
}

average(1, 2, 3, 4, 5);

# 传递列表
sub transferList {
    print("@_", "\n");
    $_[0] = 2;
}

my $a = 1;
my @b = ('a'..'d');
my %c = (
    'A' => 'g',
    'B' => 'e'
);
transferList($a, @b, %c);
print("\n");
print("\n");

12.3. 返回值

# 子程序返回值
sub add_x_y {
    my $sum = $_[0] + $_[1];
    return $sum;
}
print('1 + 2 = ', add_x_y(1, 2), "\n");
print("\n");
print("\n");

12.4. 作用域

my 局部变量
local 局部全局变量
state 静态变量(需要加上use feature 'state')

13. 引用

引用
- 在变量前加上一个右斜杠\
- my $scalar_ref = \my $foo; # 标量
- my $array_ref = \my @array; # 列表
- my $hash_ref = \my %hash; # 哈希
- my $func_ref = \&func; # 函数
- my $global_ref = \*global; # GLOB句柄
判断类型
- ref VAR 存在返回以下值, 不存在返回false
  - SCALAR
  - ARRAY
  - HASH
  - CODE
  - GLOB
  - REF

# 引用

use strict;
use warnings;

my $scalar_ref = \my $foo;    # 标量
my $array_ref = \my @array;   # 列表
my $hash_ref = \my %hash;     # 哈希
my $func_ref = \&func;        # 函数
# my $global_ref = \*global;    # GLOB句柄

# 解引用
# 已知类型 $$var @$ARRAY %$HASH
# 不知类型 @{VAR}

# @{VAR}
my $a = [1, "str", 3, 13];
print(@{$a}, "\n");

my $b = [1, "str", ['a'..'f'], 13];
foreach my $e (@{$b}) {

    my $ee = \$e;

    if(ref $ee eq 'REF') {
        print(ref($ee), ": @{$e}", "\n");
    }
    else {
        print(ref($ee), ": $e", "\n");
    }
}
print("\n");

# @$ARRAY
my @arr = (1..5);
my $temp = \@arr;
my @temp2 = @$temp;
push(@$temp, 6);
print(@$temp, "\n");
print(@arr, "\n");
print(@temp2, "\n");

# \&sub
sub add{
    my %temp_hash = @_;
    foreach my $item (%temp_hash) {
        print("item: $item", "\n");
    }
}
my %hash2 = (
    'name' => 'gendloop',
    'age' => '(50+49)/2'
);
my $add_ref = \&add;
&$add_ref(%hash2);

14. 格式化输出

15. 文件操作

15.1. open & print & close

open 三步曲: open=>print=>close

open(my $fh, '<', $file) or die "$file: $! \n"

print($fh $content)

close $fh

< 读
> 写
+> 读写
+>> 追加

sub getContent {
    local $/;
    my $content = $_[0];
    return <$content>;
}

## read
my $file = 'files/file.txt';
open(my $fh, '<', $file) or die "$file: $! \n";
my $content = getContent($fh);
close $fh;

## write
my $file_out = 'files/file_out.txt';
open($fh, '>', $file_out) or die "$file_out: $! \n";
print($fh $content);
close $fh;

## readwrite
my $file_rw = 'files/file_rw.txt';
open($fh, '+>', $file_rw) or die "file: $! \n";
my $temp = $content."\nnew line\n";
print($fh $temp);
close $fh;

## readwrite_app
my $file_rw_app = 'files/file_rw_app.txt';
open($fh, '+>>', $file_rw_app) or die "file: $! \n";
$temp = $content."\nnew line\n";
print($fh $temp);
close $fh;

15.2. 文件拷贝

# 文件拷贝

my $file_to_copy = "files/file.txt";
my $file_copy_to = "files/file_copy.txt";
open(my $hd_to_copy, '<', $file_to_copy) or die "file to cp: $! \n";
open(my $hd_copy_to, '>', $file_copy_to) or die "file cp to: $! \n";
while(<$hd_to_copy>) {
    print $hd_copy_to $_;
}
close($hd_to_copy);
close($hd_copy_to);

15.3. 文件重命名

rename(<old_name>, <new_name>);

# 文件重命名
rename("files/file_copy.txt", "files/file_renamed.txt") or die "fail to rename file: $! \n";

15.4. 删除文件

unlink(<file>);

# 删除文件
unlink("files/file_rw_app.txt");

15.5. 指定文件位置

tell($fh) 返回当前光标位置; 类型: int, 单位: 字节
seek($fh, OFFSET, START_POSITION)
- START_POSITION: 起始位置
  - 0: 文件开头
  - 1: 当前
  - 2: 结尾
- OFFSET: 偏移的字节数

# 指定文件位置
open($fh, '+>>', "files/file_renamed.txt") or die "fail to open file: $! \n";

seek $fh, 7, 0; # 从文件开头位置开始移动7个字节
while(<$fh>) {
    print($_);
    my $pos = tell $fh; # 返回当前光标的位置
    print($pos, "\n");
}
print("\n");

seek $fh, 0, 0;
my $line = <$fh>;
print($line);
print(tell $fh, "\n");

seek $fh, 0, 1;
print(tell $fh, "\n");

seek($fh, 0, 2);
print(tell($fh), "\n");

close($fh);

15.6. 获取文件信息

# 获取文件信息
$file = "files/file.txt";
my (@description, $is_B, $is_s, $is_c);
if(-e $file) {
    push(@description, ('文件上一次被访问的时间: ' . (-A _)));
    push(@description, ('是否是二进制文件: ' . ((-B _) ? 'T' : 'F'))) ;
    push(@description, ('文件索引修改时间: ' . (-C _)));
    push(@description, ('文件上一次修改时间: ' . (-M _)));
    push(@description, ('是否是一个socket(套接字): ' . ((-S _) ? 'T' : 'F'))) ;
    push(@description, ('是否是一个文本文件: ' . ((-T _) ? 'T' : 'F'))) ;
    push(@description, ('是否是block-special(特殊块)文件(如挂载磁盘): ' . ((-b _) ? 'T' : 'F'))) ;
    push(@description, ('是否是目录: ' . ((-d _) ? 'T' : 'F'))) ;
    push(@description, ('文件或目录名是否存在: ' . ((-e _) ? 'T' : 'F'))) ;
    push(@description, ('是否是普通文件: ' . ((-f _) ? 'T' : 'F'))) ;
    push(@description, ('是否是符号链接: ' . ((-l $file) ? 'T' : 'F'))) ;
    push(@description, ('文件或目录是否存在且不为0(返回字节数): ' . (-s $file)));
    push(@description, ('是否为空文件: ' . ((-z $file) ? 'T' : 'F'))) ;

    print(join("\n", @description), "\n");
}

16. 目录操作

16.1. glob

glob获取匹配的文件列表

my $fh;
my $file = "files/test.cpp";
open($fh, '>', $file) or die "$file: $! \n";
print($fh "Hello World!\n");
close $fh;

# 显示所有文件
print("\n", '# 显示所有文件', "\n");
my $dir = "files/*";
my @files = glob($dir);
foreach (@files) {
    print($_, "\n");
}

sub printArray {
    foreach (@_) {
        print($_, "\n");
    }
}

# 显示指定文件
print("\n", '# 显示指定文件', "\n");
my $pattern2 = "files/*.cpp";
@files = glob($pattern2);
printArray(@files);

# 显示隐藏文件
print("\n", '# 显示隐藏文件', "\n");
my $pattern3 = "files/.*";
@files = glob($pattern3);
printArray(@files);

# 显示多个目录下文件
print("\n", '# 显示多个目录下文件', "\n");
my $pattern4 = "./* files/*";
@files = glob($pattern4);
printArray(@files);

16.2. opendir & readdir & closedir

open 三步曲: opendir=>readdir=>closedir

opendir($hd, DIR)
@files = readdir($hd)
closedir($hd)

# 当前目录下的文件
print("\n", '# 当前目录下的文件', "\n");
my $hd;
opendir($hd, '.') or die "不能打开目录 $! \n";
@files = readdir($hd);
foreach (@files) {
    print("$_ \n");
}
close($hd);

16.3. mkdir & rmdir chdir

# 目录操作
print("\n", '# 目录操作', "\n");
=pod
创建: mkdir($dir)
删除: rmdir($dir)
切换: chdir($dir)
=cut
my $new_dir = './files/new';
my $new_dir2 = './files/new2';
mkdir('./files') or print "error: fail to mkdir './files' \n";
mkdir($new_dir) or print "error: fail to mkdir '$new_dir' \n";
mkdir($new_dir2) or print "error: fail to mkdir '$new_dir2' \n";

open($fh, '>', $new_dir . '/1.txt');
print($fh 'bingou☀\n');
close($fh);

rmdir($new_dir) or print "error: fail to rmdir '$new_dir' \n";
rmdir($new_dir2) or print "error: fail to rmdir '$new_dir2' \n";

chdir($new_dir) or print "error: fail to chdir '$new_dir' \n";
@files = glob("*");
printArray(@files);

17. 错误处理

判断
- if
- unless
- STANDARD ? TRUE : FALSE
打印
- warn
- die
- use Carp; carp, cluck; croak, confess;

# 错误处理

# if
my $fh;
if(open($fh, '<', "17_none.pl")) {
    print("success to open", "\n");
}
else {
    print("fail to open, error: $!", "\n");
}

open($fh, '<', "17_none.pl") || print("error: $!", "\n");

# unless
unless(chdir("none")) {
    print("fail to change dir, error: $!", "\n");
}

# 三元
my %fruits = (
    'p' => 'Peach'
);
print((exists($fruits{'p'}) ? $fruits{'p'} : 'not found'), "\n");
print((exists($fruits{'q'}) ? $fruits{'q'} : 'not found'), "\n");

# warn, die
chdir('none') || warn('STDERR', "\n");

# Carp
=pod
use Carp;
carp, cluck
croak, confess
=cut
use Carp;
carp("warn", "\n");
croak("die", "\n");

18. 特殊变量

待完善

$_

$_默认输入和模式匹配内容

# $_
# 默认输入和模式匹配内容
print("\n", '# $_', "\n");
foreach ('a'..'f') {
    print($_, " -> ");
}
print("end\n");

foreach ('a'..'f') {
    print;
    print(" -> ");
}
print("end\n");

18.1. $

$.获取当前句柄的行号

# $.
# 获取当前句柄的行号
print("\n", '# $.', "\n");
open(my $fh, '<', 'files/file.txt') or die "$! \n";
while(<$fh>) {
    print($_);
    print($., "\n");
}
close($fh);

18.2. $/

$/定义输入操作符(如, )在读取文本时如何确定边界

默认值: \n

# $/
# 定义输入操作符(如<STDIN>, <FILEHANDLE>) 在读取文本时如何确定边界
print("\n", '# $/', "\n");
$/ = ";";
print("input multi-line text:\n");
my $input = <STDIN>;
my @lines = split("\n", $input);
print("lines: \n");
foreach (@lines) {
    print($_, "\n");
}

$/ = "\n";
open(my $fh, '<', 'files/file.txt') or die "$! \n";
my $contents = do { local $/ = undef; <$fh>; };
print($contents, "\n");
close($fh);

18.3. $

$, 定义输出字段分隔符, 定义了在用print或say输入多个值间的分隔符

默认值undef

print("\n", '# $,', "\n");
$, = "->";
my @values = (1..5);
print(@values);
print("\n");
$, = undef;
print(@values);
print("\n");

18.4. $\

$\定义输出记录分隔符, 定义了在用print或say输出时, 会在记录末尾添加分隔符

默认值undef

# $\
# 定义输出记录分隔符, 定义了在用print或say输出时, 会在记录末尾添加分隔符
print("\n", '# $\\', "\n");
$\ = "\n";
print("1");
print("2");
print("3");
$\ = undef;
print("1");
print("2");
print("3");

19. 正则表达式

三种形式
1. 匹配 m/PATTERN/ 或 /PATTERN/
2. 替换 s/PATTERN/
3. 转化 tr/PATTERN/
操作符
1. =~ 匹配
2. !~ 不匹配

=pod
三种形式:
1. 匹配: m/PATTERN/ 或 /PATTERN/
2. 替换: s/PATTERN/REPLACEMENT/
3. 转化: tr///

操作符:
* =~ 相匹配
* !~ 不匹配
=cut

# 匹配操作符
print("\n", '# =~', "\n");
my $str1 = "name: gendloop";
if ($str1 =~ /name/) {
    print("match: 'gendloop'", "\n");
}
if($str1 !~ m/pooldneg/) {
    print("match: 'pooldneg'", "\n");
}

19.1. $`` $&`$'

`$`` 匹配部分的前一部分
$& 匹配部分
$' 未匹配的剩余部分

# 三个特殊变量
=pod
$`  匹配部分的前一部分字符串
$&  匹配的字符串
$'  未匹配的剩余字符串
=cut
print("\n", '$` $& $\'', "\n");
$str1 = "A_B_C";
$str1 =~ "B";
print("$`", "\n");
print("$&", "\n");
print("$'", "\n");

19.2. [m]/PATTERN/[MODIFIER]

修饰符
- i 忽略模式中的大小写
- x 忽略模式中的空白
- g 全局匹配. 查找所有匹配的模式, 并在每次匹配后继续查找下一个匹配

# 模式匹配修饰符
=pod
i   忽略模式中的大小写
x   忽略模式中的空白
g   全局匹配. 查找所有匹配的模式，并在每次匹配后继续查找下一个匹配。
=cut

# i
print("\n", 'i', "\n");
$str1 = "Hello WoRlD, from a maniac";
if($str1 =~ m/world/i) {
    print("match: '$&'", "\n");
}
else {
    print("match nothing", "\n");
}

# x
print("\n", 'x', "\n");
$str1 = "Line123";
if($str1 =~ m/Line 1 2 3/x) {
    print("match: '$&'", "\n");
}
else {
    print("match nothing", "\n");
}

# g
print("\n", 'g', "\n");
$str1 = "Hi \tforeigner Hi\t gendloop";
while($str1 =~ m/Hi[\s]+[a-z]+/g) {
    print("match: '$&'", "\n");
}

19.3. s/PATTERN/REPLACEMENT/[MODIFIER]

# 替换操作符
=pod
s/PATTERN/REPLACEMENT/[MODIFIER]
=cut
print("\n", '# substitute', "\n");
$str1 = "welcome to my notes";
my $str2 = $str1;
$str2 =~ s/my/gendloop's/;
print('\'', $str1, '\' => \'', $str2, "\'\n");

# i
print("\n", 'i', "\n");
$str1 = "hello, world";
$str2 = $str1;
$str2 =~ s/HELLO/Hi/i;
$str2 =~ s/WORLD/gendloop/i;
print('\'', $str1, '\' => \'', $str2, "\'\n");

# x
print("\n", 'x', "\n");
$str1 = "Blank";
$str2 = "B l a  n k ";
$str1 =~ s/$str2/NoBlank/x;
print('\'', "Blank", '\' => \'', $str1, "\'\n");

# g
print("\n", 'g', "\n");
$str1 = "1 2 3 \n 4 5 6 \n";
$str2 = '\d';
$str1 =~ s/$str2/D/;
print('\'', "1 2 3 \n 4 5 6 \n", '\' => \'', $str1, "\'\n");
$str1 =~ s/$str2/D/g;
print('\'', "1 2 3 \n 4 5 6 \n", '\' => \'', $str1, "\'\n");

19.4. tr/PATTERN/REPLACEMENT/[MODIFIER]

修饰符
- s 删除连续且相同的字符, 仅保留一个
- c 转换所有未指定的字符
- d 删除所有指定的字符

# 转化操作符
=pod
字符替换
tr/PARTTERN/REPLACEMENT/[MODIFIER]
s   删除连续且相同的字符, 仅保留一个
c   转换所有未指定的字符
d   删除所有指定字符
=cut

print("\n", '# transliteration', "\n");

$str1 = "world";
$str1 =~ tr/a-z/A-Z/;
print("world", ' => ', $str1, "\n");

# s
print("\n", 's', "\n");
$str1 = "gendloopgendloop";
$str1 =~ tr/a-z/A-Z/s;
print("gendloopgendloop", ' => ', $str1, "\n");

# c
print("\n", 'c', "\n");
$str1 = "animal";
$str1 =~ tr/a/A/c;
print("animal", ' => ', $str1, "\n");

# d
print("\n", 'd', "\n");
$str1 = "animal";
$str1 =~ tr/a//d;
print("\'animal", '\' => \'', $str1, "\'\n");