📄 perl 语言－perl 中文教程（第四章）.htm
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class=myFont><SPAN class=myFont><FONT face=宋体>翻译：</FONT></SPAN></SPAN>
<SPAN class=myFont><SPAN class=myFont>flamephoenix</SPAN></SPAN> <BR>
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<P align=center><B>第四章 列表和数组变量</B></P>
<P><A href="http://www.sun126.com/perl5/perl5-4.htm#一、列表">一、列表</A><BR><A
href="http://www.sun126.com/perl5/perl5-4.htm#二、数组--列表的存贮">二、数组--列表的存贮</A><BR> <A
href="http://www.sun126.com/perl5/perl5-4.htm#1、数组的存取">1、数组的存取</A><BR> <A
href="http://www.sun126.com/perl5/perl5-4.htm#2、字符串中的方括号和变量替换">2、字符串中的方括号和变量替换</A>
<BR> <A
href="http://www.sun126.com/perl5/perl5-4.htm#3、列表范围：">3、列表范围</A><BR> <A
href="http://www.sun126.com/perl5/perl5-4.htm#4、数组的输出：">4、数组的输出</A><BR> <A
href="http://www.sun126.com/perl5/perl5-4.htm#5、列表/数组的长度">5、列表/数组的长度</A><BR> <A
href="http://www.sun126.com/perl5/perl5-4.htm#6、子数组">6、子数组</A><BR> <A
href="http://www.sun126.com/perl5/perl5-4.htm#7、有关数组的库函数">7、有关数组的库函数</A>
<BR><BR><A
name=一、列表>一、列表</A><BR> 列表是包含在括号里的一序列的值，可以为任何数值，也可为空，如：(1, 5.3 ,
"hello" , 2)，空列表：()。<BR> 注：只含有一个数值的列表(如：(43.2) )与该数值本身(即：43.2
)是不同的，但它们可以互相转化或赋值。<BR> 列表例：<BR> (17,
$var, "a string")<BR> (17, 26 <<
2)<BR> (17, $var1 +
$var2)<BR> ($value, "The answer is
$value")<BR><BR><A name=二、数组--列表的存贮>二、数组--列表的存贮</A>
<BR> 列表存贮于数组变量中，与简单变量不同，数组变量以字符"@"打头，如：<BR> @array
= (1, 2,
3);<BR> 注：<BR> (1)数组变量创建时初始值为空列表：()。<BR> (2)因为PERL用@和$来区分数组变量和简单变量，所以同一个名字可以同时用于数组变量和简单变量，如：<BR> $var
= 1;<BR> @var = (11, 27.1 , "a
string");<BR> 但这样很容易混淆，故不推荐。<BR><BR><A name=1、数组的存取>1、数组的存取</A>
<BR> .对数组中的值通过下标存取，第一个元素下标为0。试图访问不存在的数组元素，则结果为NULL，但如果给超出数组大小的元素赋值，则数组自动增长，原来没有的元素值为NULL。如：<BR> @array
= (1, 2, 3, 4);<BR> $scalar =
$array[0];<BR> $array[3] = 5; # now @array is
(1,2,3,5)<BR> $scalar = $array[4]; # now $scalar =
null;<BR> $array[6] = 17; # now @array is
(1,2,3,5,"","",17)<BR> .数组间拷贝<BR> @result
= @original; <BR> .用数组给列表赋值<BR> @list1 =
(2, 3, 4);<BR> @list2 = (1, @list1, 5); # @list2 =
(1, 2, 3, 4, 5)<BR> .数组对简单变量的赋值<BR> (1)
@array = (5, 7, 11);<BR> ($var1, $var2) = @array; #
$var1 = 5, $var2 = 7, 11被忽略<BR> (2) @array = (5,
7);<BR> ($var1, $var2, $var3) = @array; # $var1 =
5, $var2 = 7, $var3 =""
(null)<BR> .从标准输入(STDIN)给变量赋值<BR> $var =
<STDIN>;<BR> @array = <STDIN>; #
^D为结束输入的符号<BR><BR><A name=2、字符串中的方括号和变量替换>2 、字符串中的方括号和变量替换
</A><BR> "$var[0]"
为数组@var的第一个元素。<BR> "$var\[0]" 将字符"["转义，等价于"$var".
"[0]"，$var被变量替换，[0]保持不变。<BR> "${var}[0]" 亦等价于"$var"
."[0]"。<BR> "$\{var}"则取消了大括号的变量替换功能，包含文字：${var}.<BR><BR><A
name=3、列表范围：>3、列表范围：</A> <BR> (1..10) = (1, 2, 3,
4, 5, 6, 7, 8, 9, 10)<BR> (2, 5..7, 11) = (2, 5, 6,
7, 11)<BR> (3..3) =
(3)<BR> .用于实数<BR> (2.1..5.3) = (2.1, 3.1
,4.1, 5.1)<BR> (4.5..1.6) =
()<BR> .用于字符串<BR> ("aaa".."aad") =
("aaa","aab", "aac", "aad")<BR> @day_of_month =
("01".."31")<BR> .可包含变量或表达式<BR> ($var1..$var2+5)<BR> .小技巧：<BR> $fred
= "Fred";<BR> print (("Hello, " . $fred . "!\n") x
2); <BR> 其结果为：<BR> Hello,
Fred!<BR> Hello, Fred! <BR><BR><A
name=4、数组的输出：>4、数组的输出：</A> <BR>(1) @array = (1, 2,
3);<BR> print (@array,
"\n");<BR> 结果为：<BR> 123<BR>(2) @array =
(1, 2, 3);<BR> print
("@array\n");<BR> 结果为：<BR> 1 2
3<BR><BR><A name=5、列表/数组的长度>5、列表/数组的长度</A>
<BR> 当数组变量出现在预期简单变量出现的地方，则PERL解释器取其长度。<BR> @array
= (1, 2, 3);<BR> $scalar = @array; # $scalar =
3,即@array的长度<BR> ($scalar) = @array; # $scalar =
1,即@array第一个元素的值<BR> 注：以数组的长度为循环次数可如下编程：<BR> $count
= 1;<BR> while ($count <= @array)
{<BR> print ("element $count:
$array[$count-1]\n");<BR> $count++;<BR> }<BR><BR><A
name=6、子数组>6、子数组</A> <BR> @array = (1, 2, 3, 4,
5);<BR> @subarray = @array[0,1]; # @subarray = (1,
2)<BR> @subarray2 = @array[1..3]; # @subarray2 =
(2,3,4)<BR> @array[0,1] = ("string", 46); # @array
=("string",46,3,4,5) now <BR> @array[0..3] = (11,
22, 33, 44); # @array = (11,22,33,44,5)
now<BR> @array[1,2,3] = @array[3,2,4]; # @array =
(11,44,33,5,5) now<BR> @array[0..2] = @array[3,4];
# @array = (5,5,"",5,5)
now<BR> 可以用子数组形式来交换元素：<BR> @array[1,2] =
@array[2,1];<BR><BR><A name=7、有关数组的库函数>7、有关数组的库函数</A>
<BR>(1)sort--按字符顺序排序<BR> @array = ("this", "is",
"a","test");<BR> @array2 = sort(@array); # @array2
= ("a","is", "test", "this")<BR> @array = (70, 100,
8);<BR> @array = sort(@array); # @array = (100, 70,
8) now<BR>( 2)reverse--反转数组<BR> @array2 =
reverse(@array);<BR> @array2 = reverse sort
(@array);<BR>(3)chop--数组去尾<BR> chop的意义是去掉STDIN（键盘）输入字符串时最后一个字符--换行符。而如果它作用到数组上，则将数组中每一个元素都做如此处理。<BR> @list
= ("rabbit", "12345","quartz");<BR> chop (@list); #
@list = ("rabbi", "1234","quart") now<BR>(
4)join/split--连接/拆分<BR> join的第一个参数是连接所用的中间字符，其余则为待连接的字符数组。<BR> $string
= join(" ", "this", "is","a", "string"); # 结果为"this is a
string"<BR> @list =
("words","and");<BR> $string = join("::", @list,
"colons"); #结果为"words::and::colons"<BR> @array =
split(/::/,$string); # @array = ("words","and", "colons")
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