只用于当前作用域不自动传递给所调用子程序

Vine’sPerl

our$x=7;our$y=17;suba

Vine’sPerl Lesson

my$x=10;local$y=5;print"ax$x,ay$y\n";}subbprint"bx$x,

ax10,ay5有字典变量x，有动态变量y，都是在a中定义bx, ax10,ay5有字典变量x，有动态变量y，都是在abx7by5有全局变量x(用our定义的)，有动态变量y(在a中定义的1Vine’sPerl"my","local",andVine’sPerl

Vine’sPerl字典作用mydeclaresalexicalvariabletotally

•Perl程序的一般结构(务必用my定义变量 fromtheoutside可以模仿C语言的auto要模仿C语言的static变量，可以这样{my($s)= #单独用对{}，在里面定义mysubgetnext{$s++;}#$s对外不可见，但每次调用getnext之间都保留$s的printgetnext;printgetnext;print全局作ourusevarsqw(变量列表),例usevarsqw($frob@mung

#!/usr/local/bin/perl-wusestrict;uselib"path";usemodule_names;require…maincodesubroutine1{…}subroutine2{…}subroutine3{…}…

回家作业(学号-用级数展开sin(x)编写子程序submysin，第个参数是x,第个参数是n,返 –缺省情况下都是全局变量,可以用$v,$::v,或

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10 0.841470984807897 Vine’sPerlFileHandling---StandardStandardfilehandles(Already

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Vine’sPerl datafollowing STDINinput,canbeSTDOUToutput,canbeSTDERRoutput,can’tberedirected,forerrorWritetofile,printSTDERRprint@lines; #defaultisSTDOUTprintFD$a, #notprintFD,Readfile,the<FILEHANDLE>,diamondoperator“<>”while($line=<STDIN>){};#readoneline@lines=<>;#readfilelistedin@ARGV#onebyone.When@ARGVis#empty,readfromSTDIN5

特 httpgethtt |perlx usemy@lines=grep chomp@lines;foreach(@lines){$_=~ $_=~}print"$_\n"foreach@lines;想想如何将这 工具互动起来7Vine’sPerlFileHandling---Vine’sPerlOpenauser

Vine’sPerlsubnameVine’sPerlsubfunc1($){…}#不带\的@和%不带\的@和%必须放在最后,ForForFor

open(FD,open(FD,open(FD,

submygrep(&@)sub

#&代码mygrep{/1+/}$a,$b#*句柄myopenHANDLE,ForpipeForpipe

open(FD,"可执行文件名open(FD,"|可执行文件名

submypush(\@@){my$list=shift;push@$list,@_;

#\@isarray-#\%ishash–ref,etc#@isarray,lastone–+>截断文件并打开读写 +<不截断文件并打开读写Close open(FD,"ls-la|");print #DOS$oldFD=select(FD);#chooseadefault6

subpi(){3.1416}#constanctfunctionprintpi+2;#print5.1416,not3.1416#takeitasprint(pi(+2))ifnot若用了函 常数可以用use pi=>3.1415更方这样定义的常数不用带前缀$,直接用8Vine’sPerl

Kindly

Vine’sPerl#!/usr/bin/perl-wusestrict;subpi_proto(){3.1416}subpi_normal{3.1416}submypush(\@@){my$list=shift;push@$list,@_;

pi_proto+2ispi_normal+2islistis(1,2,3,

循环的continuelocal和our变}print"pi_proto+2is",pi_proto+2,"\n";print"pi_normal+2is",pi_normal+2,"\n";mypush@list,1,2,3,4;printprint"listis(",(join",",@list),9

–函数原型 函数，左值函SubroutineVine’sPerlSubroutineDefineandcallananonymousmy$subref=sub{$_[0]+my$add=$subref;#makeacopyofsubroutine-print&{$add}(1,2),"\t",&$add(1,2),"\t",$add-Lvaluesubroutine

Vine’sPerlFileHanle---Binarymode Offsetin$var,nottotheread(FD,$var,$len,#read20bytesfromfileopen(FILE,subLsub:lvalue{$_[$index];#don'tsayreturn$_[$index]}my@a=qw(Imyteaching$"="

read(FILE,$buffer,20);seek(FD,$pos,

0:Beginof1:Currentposition2:EndoffileprintLsub(2,@a)='learning';#函数返回作值，修改为print@a\n";#@a

l(FD)#positionofsysopen(),sysread(),$integer=fileno(FD); FileHandle---FileTests,isPerlCheckifafile/dir/symbolic_linkdie"Filemissing!"ifnot-eCheckifnameisa -dCheckifnameisaregularfile:-fLotsmore-xoperationsinGlob,returnalistofmatchedfile/dir@txt_files=@root_files=<c:/*.*>;#PC/MS-OS@gif_files=这里的*?是文件名通配符,不能按照perlRE规则来理解

FileSystemPipelinesinVine’sPerlpipe()thenfork(),closeonesideuseVine’sPerlpipeREADHANDLE,WRITEHANDLEordie"Can'topenmymy$child_pid=die"Failtofork!\n"ifnotdefinedif($child_pid==0){#inchildprint"I'mchild.Mypidisclose$message=" ofather.".intrand100.".";print"Childsend\"$message\"tofather.\n";printWRITEHANDLE$message;close}else#inprint"I'mfather,pidis$$.Childpidisclose$message=join"",<READHANDLE>;print"Fatherreceived:$message\n"; Vine’sPerlTheUNIXfork()andVine’sPerlfork()TheonlywaytostartanewReturnchildpidtoparent,return0toCopyalldatasections.CodeareusuallyFiledescriptorsareexec(str)loadsanewimage(code),neverif(0