Manipulating Perl arrays: shift, unshift, push, pop - Perl Maven

If you imagine the array starting on the left hand side, the shift function will move the whole array one unit to the left. The first element will "fall ... Togglenavigation PerlMaven PerlTutorial Pro Login Register Books Typekeyword: Archive About Perltutorial Introduction InstallingandgettingstartedwithPerl TheHash-bangline,orhowtomakeaPerlscriptsexecutableonLinux PerlEditor HowtogetHelpforPerl? 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Haveexceededthemaximumnumberofattempts(1000)toopentempfile/dir Useofimplicitsplitto@_isdeprecated... Other MultidimensionalarraysinPerl MultidimensionalhashesinPerl MinimalrequirementtobuildasaneCPANpackage Statementmodifiers:reversedifstatements Whatisautovivification? FormattedprintinginPerlusingprintfandsprintf ManipulatingPerlarrays:shift,unshift,push,pop array shift unshift push pop Prev Next Aswellasallowingdirectaccesstoindividualarrayelements, Perlalsoprovidesvariousotherinterestingwaystodealwitharrays. Inparticular,therearefunctionsthatmakeitveryeasyandefficient touseaPerlarrayasastackorasaqueue. pop Thepopfunctionwillremoveandreturnthelastelementofanarray. Inthisfirstexampleyoucanseehow,givenanarrayof3elements,thepopfunction removesthelastelement(theonewiththehighestindex)andreturnsit. my@names=('Foo','Bar','Baz'); my$last_one=pop@names; print"$last_one\n";#Baz print"@names\n";#FooBar Inthespecialcaseoftheoriginalarraybeingempty,thepopfunction willreturnundef. push Thepushfunctioncanaddoneormorevaluestotheendofanarray. (Well,itcanalsoadd0values,butthat'snotveryuseful,isit?) my@names=('Foo','Bar'); push@names,'Moo'; print"@names\n";#FooBarMoo my@others=('Darth','Vader'); push@names,@others; print"@names\n";#FooBarMooDarthVader Inthisexampleweoriginallyhadanarraywithtwoelements. Thenwepushedasinglescalarvaluetotheendandourarray gotextendedtoa3-elementarray. Inthesecondcalltopush,wepushedthecontentofthe@others arraytotheendofthe@namesarray,extendingittoa5-elementarray. shift Ifyouimaginethearraystartingonthelefthandside, theshiftfunctionwillmovethewholearrayoneunittotheleft. Thefirstelementwill"falloff"thearrayandbecomethefunction'sreturnvalue. (Ifthearraywasempty,shiftwillreturnundef.) Aftertheoperation,thearraywillbeoneelementshorter. my@names=('Foo','Bar','Moo'); my$first=shift@names; print"$first\n";#Foo print"@names\n";#BarMoo Thisisquitesimilartopop,butitworksonthelowerendofthearray. unshift Thisistheoppositeoperationofshift.unshiftwill takeoneormorevalues(oreven0ifthat'swhatyoulike)andplaceitatthe beginningofthearray,movingalltheotherelementstotheright. Youcanpassitasinglescalarvalue,whichwillbecomethe firstelementofthearray.Or,asinthesecondexample,youcanpassasecond arrayandthentheelementsofthissecondarray(@othersinourcase) willbecopiedtothebeginningofthemainarray(@namesinourcase) movingtheotherelementstohigherindexes. my@names=('Foo','Bar'); unshift@names,'Moo'; print"@names\n";#MooFooBar my@others=('Darth','Vader'); unshift@names,@others; print"@names\n";#DarthVaderMooFooBar Prev Next Writtenby GaborSzabo Publishedon2013-02-06 Comments Inthecomments,pleasewrapyourcodesnippetswithin

tagsandusespacesforindentation. commentspoweredbyDisqus Ifyouhaveanycommentsorquestions,feelfreetopostthemonthesourceofthispageinGitHub.SourceonGitHub. Commentonthispost Author:GaborSzabo GaborwhorunsthePerlMavensitehelpscompaniessetuptestautomation,CI/CD ContinuousIntegrationandContinuousDeploymentandotherDevOpsrelated systems. GaborcanhelprefactoryouroldPerlcode-base. HerunsthePerlWeeklynewsletter. ContactGaborifyou'dliketohirehisservice. BuyhiseBooksorifyoujustwouldliketosupporthim,doitviaPatreon. English Français Italiano Português 简体中文 aboutthetranslations undef,theinitialvalueandthedefinedfunctionofPerl