Data Display Debugger.ppt

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1、ADDDTutorialElenaJakubiak&LarissaWineyWhatisDDDDDDstandsforDataDisplayDebuggerDDDisavisualinterfacetothecommand-lineGDBdebuggerWhyDDD?It’sintuitiveIt’sfast“Ijustuseprint()statements”That’slikesewingclothesusinganeedleandthreadinsteadofasewingmachineGettingStartedCopy

2、thesampleprogramstoyourdirectory%cp/r/uxpdworkshop/DebugLab/*.Compileyourprogramusingthe–gflag%g++-gfactorial.cpp–ofactorialRunyourprogram,rightnow,we’llstartwithfactorial(anyeasyprogramtostartwith)%factorialSoYouHaveaBugWhatdidyouexpecttheprogramtodo?Itshouldtakethe

3、factorialofanumberi.e.6!=6*5*4*3*2*1=720(1!=1)Anyideaswhatwentwrong?Youdidn’twritethiscodeYoucouldreadthecodeandthentrytounderstandabunchofitandthenputinprint()statementsYoucouldwalkthroughitinthedebugger(Hint:Choosethedebugger)StartingDDDOpenyourexecutableprograminD

4、DD(DDDknowswhatsourcecodetousebecauseyoucompiledwiththe–gflag)%dddfactorial&CustomizingDDDLinenumbers:SourceDisplayLineNumbersDockingtoolbars:EditPreferencesSettingBreakpointsIftheprogramisstuckinaninfiniteloop,thenwewanttosetabreakpointinthewhileloopRight-clickont

5、helinenumberofthewhile(number<1)SelectSetBreakpointThereshouldnowbeastop-signatthatlineStarttheProgramAtthetopofthescreen,select“Run”tostartyourprogramThiscanalsobefoundinthe‘program’menuIfDDDasksforargumentstoyourprogram,justleaveitblankTheprogramwillhaltandpromptyo

6、uforinputinthebottomofthewindowEnterasmallnumber:somethingthatshouldfinishinlessthanasecond.Itshouldstopagainatthebreakpoint.(Theblackarrowindicatesthenextlinetobeexecuted)Next,Hover,andStepUseNexttomovethroughtheprogramonelineatatimeAftereachNextyoucanholdyourcursor

7、overeachvariabletoseethevalueThisiscalledhoveringUsethistowatchthevaluesinfactorial,numberandstartnumberThisalwaysdisplaysthevariable’svalueatthecurrentlineofexecutionNoteStepwillmovedowntheprogram,onelineatatime.Itwillalsostepintofunctioncallsifthereareany.Nextwould

8、alsomovedownonelineatatime,butwouldskipfunctioncalls.FixingtheBugSo,what’sgoingwrong?LeaveDDDopenOpenthecodeinyourfavoriteeditor(fa