11-debugging-your-sas-programs

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1、The Little SAS Book: A Primer, Fifth EditionChapter11:DebuggingYourSASPrograms"Problemsthatgoawaybythemselvescomebackbythemselves."MarcyE.DavisFromTheOfficialExplanationsbyPaulDickson.Copyright1980byDelacortePress.Reprintedbypermissionofthepublisher.11.1WritingSASProgramsThatWorkIt'snotalwayseasyto

2、writeaprogramthatworksthefirsttimeyourunit.EvenexperiencedSASprogrammerswilltellyouit'sadelightfulsurprisewhentheirprogramsrunonthefirsttry.Thelongerandmorecomplicatedtheprogram,themorelikelyitistohavesyntaxorlogicerrors.Butdon'tdespair,thereareafewguidelinesyoucanfollowthatcanmakeyourprogramsrunco

3、rrectlysoonerandhelpyoudiscovererrorsmoreeasily.MakeProgramsEasytoReadOnesimplethingyoucandoisdevelopthehabitofwritingprogramsinaneatandconsistentmanner.Programsthatareeasytoreadareeasiertodebugandwillsaveyoutimeinthelongrun.Thefollowingaresuggestionsonhowtowriteyourprograms:nPutonlyoneSASstatement

4、onaline.SASallowsyoutoputasmanystatementsonalineasyouwish,whichmaysavesomespaceinyourprogram,butthesavedspaceisrarelyworththesacrificeinreadability.nUseindentiontoshowthedifferentpartsoftheprogram.IndentallstatementswithintheDATAandPROCsteps.ThiswayyoucantellataglancehowmanyDATAandPROCstepsthereare

5、inaprogramandwhichstatementbelongstowhichstep.It'salsohelpfultofurtherindentanystatementsbetweenaDOstatementanditsENDstatement.nUsecommentstatementsgenerouslytodocumentyourprograms.Thistakessomedisciplinebutisimportant,especiallyifanyoneelseislikelytoreadoruseyourprogram.Everyonehasadifferentprogra

6、mmingstyle,anditisoftenimpossibletofigureoutwhatsomeoneelse'sprogramisdoingandwhy.Commentstatementstakethemysteryoutoftheprogram.TestEachPartoftheProgramYoucanincreaseyourprogrammingefficiencytremendouslybymakingsureeachpartofyourprogramisworkingbeforemovingontowritethenextpart.Ifyouwerebuildingaho

7、use,youwouldmakesurethefoundationwaslevelandsquarebeforeputtingupthewalls.Youwouldtesttheplumbingbeforefinishingthebathroom.Youarerequiredtohaveeachstageofthehouseinspectedbeforemovingontothenext.Thesamesho