perl数据操作

一次给多个变量赋值

($a, $b, $c) = ("aaa", "bbb", "ccc");
print "$a  $b  $c\n";

或者

@ls = ("aaa", "bbb", "ccc");
($a, $b, $c) = @ls;
print "$a  $b  $c\n";

散列

%longday =
(
        "Sun" => "Sunday",
        "Mon" => "Monday",
        "Tue" => "Tuesday",
        "Wed" => "Wednesday",
        "Thu" => "Thursday",
        "Fri" => "Friday",
        "Sat" => "Saturday",
        "All" => ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]
);

print $longday{"Sun"}."\n";
print $longday{"All"}[1]."\n";

遍历散列（如环境变量）

foreach $key (keys %ENV) {
        print "$key = $ENV{$key}\n";
}

或

while(($key, $value) = each(%ENV)) {
        print $key." = ".$ENV{$key}." = ". $value ."\n";

}

数组

给数组赋值

@ls = "a" .. "z";
for(@ls){print $_, "\n";}

利用qw定义数组，可以省去引号和都好

@ls = qw(aaa bbb ccc ddd);
for (@ls){print $_, "\n";}

qw允许用其它符号代替括号，甚至是注释符号

@l = qw#aaa bbb ccc ddd#;

数组扩容

@a = ("a", "b");
@a = (@a, "x");
print $a[2]; 输出x

push和pop

push从下标加1开始追加，

pop从下标最大开始减

@ls = qw(a b c);
for(@ls){print $_, " ";}
print "\n";
push @ls, "l";
push @ls, "m";
push @ls, "n";
for(@ls){print $_, " ";}
print "\n";
@xyz = qw(x y z);
push @ls, @xyz;
for(@ls){print $_, " ";}
print "\n";
print " POP:", pop @ls;
print " POP:", pop @ls;
print " POP:", pop @ls;
print "\n";
for(@ls){print $_, " ";}
print "\n";

输出：

a b c
a b c l m n
a b c l m n x y z
POP:z POP:y POP:x
a b c l m n 

排序和翻转

@ls = sort qw(b a c);  得到 a b c
@ls = reverse qw(a b c); 得到 c b a

循环的时候

@a = ("asd", "bsd");
@a = (@a, "csd");
foreach (@a)
{
     next if /b/;    next相当于continue，这里指跳过“bsd”
     print;          循环体内，$_代表当前的循环内容，命令中如果没有操作数，则默认是对$_操作

     switch 

     case /^a/ {...}

     case /^b/ {...}

     case /^c/ {...}
}

几种switch（last相当于break）

foreach (@a)
{

     switch: 

     {

          if(/^a/) {...; last switch} 

          if(/^b/) {...; last switch}

          if(/^c/) {...; last switch}

     }

     或者

     switch: 

     {

          /^a/ && do {...; last switch};

          /^b/ && do {...; last switch};

          /^c/ && do {...; last switch};

     }

}

用户输入

$line = ;
print $line;

通过STDIN的方式，获取的输入内容是带有换行符的，因此，在实际使用中，需要用chomp，获取不带换行符的用户输入。

$line = ;
chomp $line;
print $line;

或

chomp ($line = );
print $line;

判断变量是否被定义

if (defined($a)) {print "defined", "\n";} else {print "undefined", "\n";}
$a=123;
if (defined($a)) {print "defined", "\n";} else {print "undefined", "\n";}

输出

[root@server2 pl]# ./a.pl
undefined
defined

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转载于:http://blog.itpub.net/26239116/viewspace-2125607/