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Basic operation
check version : perl -v
perldoc
perldoc perl
man perl
CPAN
-w???????????? enable warning， in command line
use warnings????? enable warning， 5.6.x以后perfer
q{}=''?????????? won't interpolate
qq{}=""????? interpolate variables
qx{}=``
qw{}
m//?????? pattern matching
s///?????? replace
tr///???? interpolate $ a d @ variables
ord?????? get the numeic value of a character,? e.g. ord("#")
[-564]???? 从后往前数第564个元素
List???? （1,2,3）
Array????? @a=(1,3)
增加元素???? @a=(@a,4);
$count=@a???? $count等于array的长度
使用array做index访问array????????????? @index = (0,2);
??????????????????????????????????????? print @a[@b];
reverse
push?????? add last element in array
pop??????? remove last element in array
shift????? remove a element from start of an array
unshift??? place an element at the start of an array
hash?????? %link = (
???????????????????? A=>1,
???????????????????? B=>2,
???????????????????? C=>3,
???????????????????? );
delete
keys
values
each
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Regular expression
=~???? binding operator
!~????? negetive binding operator
Q?? E??? 不转义metacharacter
anchoring matches?? ^ beginning?? $?? end
[abc]????? 包含any one of a,b,c
[^abc]????? caret symbol ^? 不包含
hyphen?? -???? 从 。。到。。
（?i)????? prevent Perl from interpreting the search pattern as case sensitive,?? e.g. $a=~ /(?i)(Heathw?)/
Perl5.6.0支持
[[:alpha:]]?? alphabetic characters
[[:alnum:]]??? alphabetic characters or numeric characters
[[:digit:]]??? 0 to 9
[[:lower:]]??? lowercase letters
[[:upper:]]??? upcase letters
[[:punct:]]??? punctuation character标点符号
（a|b|c)??? 相当于? [abc]???? alternatives operator |
但是? | 更灵活??? e.g. (aa|ws|edc)
Quantifiers
*???? to find the first match that occurs
+????? to find a match using as few repeats as possible,but allow at least one repeat
?????? to find a match using zero repeats if possible
Backreference
找到符合的pattern后，perl将value存到$1,$2,$3....
Search-and-replace
s/e/a/
/i 不区分大小写
/g? 全局替换
/m? think m for multiple lines，看做多行，这时锚定针对每一行，而非整个字符串
/s?? Let . match n ， 忽略新行
/G?? match 最后一个
/x??? Ignore most whitespace and allow comments
Transliteration
tr/abcd/efgh/??? replace?? a->e?? b->f? c->g?? d->h
/d?? 删除无对应的字符，??? e.g.?? $a=~tr/Cre/Db/d?????? e没有对应的字符，e将被删除
split /分隔符/,str
join
?#??? inline comments???
?:??? 如果没有match，指定的backreference将不会为空，而是存放下一个match。 Prenvent Perl from backreferencing the empty value.
lookaheads????? ?=?? only match if the preceding word is the one you have specified??,指定后面跟着的文字???
negative lookaheads???? ?!
lookbehinds?????? ?<?????? only match if the following word is the one you have specified??? ， 指定前面的文字,e.g.? $a =~ s/(?<=wedding) day/ vows/?? 将wedding day中的day换为vows
negative? lookbehinds??????? ?<!
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Variables and parameters
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$_????? global scalar for pattern-matching and subsitution operation,and also used by filehandlers when reading in and wrinitng to files.
@_????? 子程序的输入参数
@ARGV?? store the inout command-line arguments for use in scripts.
$ARGV??? contains the name of the current file when reading from the null filehandle <>
$(number)??? backreference,contains the regular expression pattern memory.
$&?????? contains the string that was last successfully mathced in a pattern
$`????? contains the string that preceded the last successful pattern match
$'????? contains the string that was after the last successful pattern match
$+????? contains the last string that was matched to a grouped subpattern in the last search.
@+?????? it is array,refer to the back pointer position of the last successful match in the referenced string
@-????? list the front pointer's position
input/output variables
$.????????? 最后读取的filehandle的行数
$/????????? input record separator
$????????? out put reord separator
$|????????? internal flag， usually set to zero
$,????????? output filed separator
$"????????? output field separator when a array variable has been interpolated into a double-quoted string
$-????????? contains the number of lines still left to print for the default filehandle.
$??????????? 进程的退出状态
$@?????????? eval()的错误信息
$!?????????? 当前的errno的值， 系统的错误信息,error message
File handle
STDIN
STDOUT
STDERR
open FIEHANDLE,"c:testabc.txt"
<...>??? diamond operator,? readline operator
reading from te command line????
?????? while (<>)
reading from entire files????
?????? my $file= <FILEHANDLE>
reading in a while loop
?????? while(<FILEHANDLE>)
reading with an array
?????? @book=<FILEHANDLE>
select???? 改变默认的输出句柄,(默认会使用 STDOUT)
