CS 115 Final Review Quiz

Transcription

1 CS115FinalReviewQuiz December11,2008 Rules ReferencematerialontheSTLclassesandalgorithms,aswellasfunctions thatoperateonc strings,isincludedattheendofthisdocument. Youmustbrieflyexplainyouranswerstoreceivepartialcredit. Whenasnippetofcodeisgiventoyou,youcanassumethatthecodeis enclosedwithinsomefunction,evenifnofunctiondefinitionisshown.you canalsoassumethatthemainfunctionisproperlydefinedandthatthe iostream,fstream,iomanip,vector,algorithm,string,cstring, andcmathlibrarieshavebeenincludedatthebeginningoftheprogram. Whenyouareaskedtowriteasnippetofcode,youmayalsoassumethatitis enclosedwithinsomefunctionthatanynecessarylibrarieshavebeen included. Whenyouareaskedtowriteacompleteprogram,youmustwritethe #includestatements,theint main(),etc.inyoursolutiontoreceivefull credit. Alineconsistingsolelyof representsoneormoreunspecifiedc++ statements,someofwhichmaychangethevaluesofprogramvariables.

2 Problem1:15points. Matchthefollowingdescriptionswiththetermtheydescribebywritingthattermin thespaceprovided.thechoicesoftermsare: this destructor class dynamicmemoryallocation overloading operator iterator container Notalltermswillbeused. (a) (b) (c) (d) (e) Multiplefunctionsoroperatorswiththesamenamebutdifferentinput datatypes Afunctionthatisautomaticallycalledwhenanobjectisdeleted Theuseofnewordeletetocreateavariableorobject Aclass,suchastheSTL svectorclass,thatstoresacollectionofobjects. Apointertotheobjectwhosememberfunctionisbeingcalled.

3 Problem2:10points. Correctthefollowingprogramsothatitsbehaviormatchestheinitialcomment. /* Create a Student whose name is "Donald Duck" and whose ID is 5050, and use the Print function in the Student class to print the student s name and ID */ #include <iostream> #include <string> using namespace std; class Student { string name; long id_num; } Print() { cout << "Name: " << name << endl << "ID: " << id_num << endl; } int main { Student.name = "Donald Duck"; Student.id_num = 5050; Student.Print(); } return 0;

4 Problem3:10points. Writeasnippetofcodethatdoesthefollowing: Declaresavectorofstrings Addsthreestringstothevector(yourchoice keepitclean). Sortsthevector Emptiesthevector Printsthefinalsizeofthevector. Remembertousethereferencematerialattheendofthistest.

5 Problem4:10points. (a) What swrongwiththefollowingsnippetofcode?(youdon thavetofixit; justclearlystatewhat swrong.) /* Set C-string a equal to "pear" and b equal to "apple". Then copy b to a and print out a. */ char* a; char* b = "apple"; strcpy (a, b); cout << a; (b) AssumethattheWordclasshasbeendeclaredwiththefollowingprivate datamembers(inadditiontoabunchofpublicfunctions): private: char * data; int length; Youareinchargeofdefiningwhatthe*operatormeansforthisclass;youdecide thatw1 * w2,wherew1andw2arewords,willreturntheproductofthelengthsof the data stringsw1andw2.someonehasalreadywrittentheskeletonforyou;you justneedtofillitin.foryourreference,thedefinitionofthe+operatorisalso shown. // Addition operator Word Word::operator + (const Word& other) const { Word temp; temp.length = this->length + other.length; temp.data = new char [temp.length + 1]; strcpy (temp.data, this->data); strcat (temp.data, other.data); return temp; } // Multiplication operator: fill this in int Word::operator * (const Word& other) const { }

6 Problem5:15points. Forthisproblem,youmustwriteaclassdefinitionforaclassnamedRectangle thatcontainsthefollowing: Lengthandwidth(asprivatedataoftypedouble) Prototypeforadefaultconstructor PrototypeforafunctioncalledSetSides.Thisfunctionwilltaketwo doublesasinputsandreturnabool. PrototypeforafunctioncalledGetArea.Thisfunctionwillreturnthearea oftherectangle. PrototypeforafunctioncalledGetDiag.Thisfunctionwillreturnthelength oftherectangle sdiagonal.

7 Problem6:20points. Inthisproblem,youwillwritedefinitionsforthefunctionsintheclassRectangle. Hereisalittlebitmoreinformationaboutthefunctions. Thedefaultconstructorwillinitializethelengthandwidthto1. TheSetSidesfunctionwillworkasfollows: o Ifoneorbothoftheinputsislessthanorequaltozero,itwillreturn false. o Otherwise,itwillsetthelengthequaltothefirstinputandthewidth equaltothesecondinput.thenitwillreturntrue. TheGetAreafunctionwillreturntheareaoftherectangle(lengthtimes width). TheGetDiagfunctionwillreturnthelengthoftherectangle sdiagonal. Recallthatthelength,width,anddiagonalformarighttrianglethatobeythe relationshipa 2 +b 2 =c 2,whereaandbarethelengthandwidthandcisthe diagonal.assumethat<cmath>isincluded.

8 Problem7:20points. AssumethattheclassdefinitionsyouwroteinProblems5and6arelocatedinafile calledrectangle.hinthesamedirectoryastheprogramyou reabouttowrite. WriteacompleteprogramthatusestheRectangleclassfromrectangle.hto dothefollowing: CreateoneRectangleobjectwithlength5.5andwidth3 Asktheusertosupplythelengthandwidthofanotherrectangle,andcreatea Rectangleobjectforthatonetoo.Youcanassumethattheuserentersa validlengthandwidth. UsetheGetAreafunctiontocomputetheareaofbothrectangles,andprint ONLYtheareaofthelargerone.

9 REFERENCE C stringfunctions: strlen InputisaC string.returnsthelengthofthestring(notincludingthe nullterminator). Usageexample:length = strlen(name); strcat InputistwoC strings.appendsthesecondstringtotheendofthefirst string(thefirststringischanged,butthesecondisnot). Usageexample:strcat(str1, str2); strcpy InputistwoC strings.copiesthesecondstringtothefirststring, overwritingtheoriginalcontents. Usageexample:strcpy(str1, str2); strcmp InputistwoC strings.returns0iftheyarethesame,anegativenumber ifstr2isalphabeticallygreaterthanstr1,andapositivenumberif str1isgreaterthanstr2. Usageexample:if(strcmp(str1, str2) > 0) Vectormemberfunctions: begin() Returnsaniteratortothevector sfirstelement clear() Removesallelementsfromthevector empty() Returnsaboolwhichistrueifthevectorisempty(haszero elements)andfalseotherwise end() Returnsaniteratorpointingjustpastthevector slast element pop_back() Removesthelastelementfromthevector push_back(value) Insertsvalueasanewelementattheendofthevector size() Returnsthenumberofelementsinthevector STLalgorithms(NOTmemberfunctions) Hereiter1anditer2areiteratorspointingtoelementsofanSTLclasssuchas vector. binary_search(iter1, Returnstrueifvalueisfoundintherange iter2, value) betweeniter1anditer2,falseotherwise count(iter1, iter2, Returnsthenumberoftimesvalueappearsinthe value) rangebetweeniter1anditer2 reverse(iter1, iter2) Reversestheorderoftheelementsbetweeniter1 anditer2 random_shuffle(iter1, Randomlychangestheorderoftheelements iter2) betweeniter1anditer2 sort(iter1, iter2) Sortstheelementsintherangebetweeniter1and iter2inascendingorder