perl语言讲义03.pdf

Spring,2009

Perl入门和提高Lesson3

周晓方
[e-mail]

1
Spring,2009
Sample
•@s里面是一个spice文本，请把电容的容量加倍，
电阻的阻值减半；不考虑续行。
•提示，电容卡的格式是"C名称Node1Node2容量"
@s=('RIN1210MEG',
'EGAIN3012100K',
'RP1341K',
'CP1401.5915UF',
'ROUT5610');
s/^(C(\S+\s+){3})([0-9\.]+)/$1.($3*2)/eforeach@s;
/^R/ands/([0-9\.]+)(\S*)$/($1\/2).$2/eforeach@s;
printjoin"\n",@s;
别忘了除法运算符/要转义

RIN125MEG
EGAIN3012100K
RP1340.5K
CP1403.183UF
ROUT565
2
Spring,2009
join,map,split,reverse,sort,grep
join("\n",@array);#returnstring
map("$_\n",@array);#returnarray
printjoin"\t",map$_*$_,1..10;
printjoin"\t",mapintrand(20),1..10;
split(/pattern/,"string");#returnarray
@list=split(//,"ABCDEFGHI");#qw(ABCDEFGHI)
@list=split(/:/,"12:34:56:78",3);#qw(123456:78)
reverse(@array);#returnarray数组反序
scalarreverse(@array);#合并成字符串，字符反序
%new_hash=reverse%old_hash;#交换哈希表的key和val
sort(@array);#returnarray
sort{$acmp$b}@list;#用法很丰富，参考perlop
sort{$a<=>$b}@list;
sort{-($a<=>$b)}@list;
grep(/pattern/,@array);#returnfilteredarray
@foo=grep(!/^#/,@bar);#removelinesstartwith#

3
Spring,2009
Hash表用于计数—单词统计
!/usr/bin/perl-w
usestrict;
=====Wordcount:
my@lines=<DATA>;#Readindata
chomp@lines;#RemoveCRLFthe9
my$line=lcjoin"",@lines;test1
$line=~s/[^a-z]+//g;#remove,:.()'explicitly1
my@words=split//,$line;you2
my@chars=split//,$line;normal1
print"=====Listofallwords:\n";file2
printjoin"\t",@words;exactly1
my($word,$char,$count,%words,%chars);that1
$words{$_}++foreach@words;my1
$chars{$_}++foreach@chars;
print"\n\n=====Wordcount:\n";……
print"$word\t$count\n"=====Charcount:
while($word,$count)=each%words;w1
print"\n\n=====Charcount:\n";a27
print"$char\t$count\n"r26
while($char,$count)=each%chars;x4
1;d11
__END__y9
Thereisoneminordifference:ifvariablesu4
aredeclaredwithmyintheinitialization
h16
sectionofthefor,thelexicalscopeofthose
…………

4
Spring,2009
回家作业
•统计当前Win32系统上的TCP链接类型和数目，提
示1：用netstat-n-a命令，如下小型服务器上的统计
my@lines=split"\n",`netstat-n-a`;
CLOSING4
然后历遍每一行进行统计，最后TIME_WAIT202
的统计结果输出成如下的格式：CLOSE_WAIT1
LISTENING128
TIME_WAIT5FIN_