perl資料操作

liiinuuux發表於2016-09-26
一次給多個變數賦值
($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";

雜湊
%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";

遍歷雜湊（如環境變數）
foreach $key (keys %ENV) {
        print "$key = $ENV{$key}\n";
}
或
while(($key, $value) = each(%ENV)) {
        print $key." = ".$ENV{$key}." = ". $value ."\n";
}




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

利用qw定義陣列，可以省去引號和都好
@ls = qw(aaa bbb ccc ddd);
for (@ls){print $_, "\n";}
qw允許用其它符號代替括號，甚至是註釋符號
@l = qw#aaa bbb ccc ddd#;


陣列擴容
@a = ("a", "b");
@a = (@a, "x");
print $a[2]; 輸出x

push和pop
push從下標加1開始追加，
pop從下標最大開始減
@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";

輸出：
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 

排序和翻轉
@ls = sort qw(b a c);  得到 a b c
@ls = reverse qw(a b c); 得到 c b a


迴圈的時候
@a = ("asd", "bsd");
@a = (@a, "csd");
foreach (@a)
{
     next if /b/;    next相當於continue，這裡指跳過“bsd”
     print;          迴圈體內，$_代表當前的迴圈內容，命令中如果沒有運算元，則預設是對$_操作
     switch 
     case /^a/ {...}
     case /^b/ {...}
     case /^c/ {...}
}

幾種switch（last相當於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};
     }
}

使用者輸入
$line = <STDIN>;
print $line;
透過STDIN的方式，獲取的輸入內容是帶有換行符的，因此，在實際使用中，需要用chomp，獲取不帶換行符的使用者輸入。
$line = <STDIN>;
chomp $line;
print $line;
或
chomp ($line = <STDIN>);
print $line;

判斷變數是否被定義
if (defined($a)) {print "defined", "\n";} else {print "undefined", "\n";}
$a=123;
if (defined($a)) {print "defined", "\n";} else {print "undefined", "\n";}
輸出
[root@server2 pl]# ./a.pl
undefined
defined




























來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/26239116/viewspace-2125607/，如需轉載，請註明出處，否則將追究法律責任。

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