KENDRIYA VIDYALAYA SANGATHAN (KOLKATA REGION) Second Pre Board Examination (2014-15) COMPUTER SCIENCE (Theory) Class-XII Marking Scheme Ques. 1 a) [1] Automatic Type Conversion Type casting It is also called implicit type It is also called explicit type conversion. conversion In this type, conversion is performed It is user-defined that forces an by compiler. expression to be of specific type. Automatic conversion takes place Here conversion takes place when it automatically when data types are appears as (type) expression intermixed in an expression. Conversion takes place always upto Conversion takes place to the specific the type of the largest operand. data type that appears in type. Suitable example [1] b) i) iostream.h [2 x ½ =1] ii) string.h c) #include<iostream.h> [½ x4=2] class MEMBER int Mno; float Fees; public: void Register ( ) cin>>mno>>fees; void Display( ) cout<<mno<<" : "<<Fees<<endl; 1
; void main() MEMBER d; d.register(); d.display(); d) JjIANS! [2] e) [3] 20, 25, 30, 20, 25, 30, 35, Number=34 f) iii) ######99-@@999 iv) ####99-@@@999 [1] Justification [1] Ques. 2 a) [2] We will make the function inline only when it is small as if we make large function inline, there would be heavy memory penalty. When the function becomes inline, the compiler does not have to jump to function and then jump back to called function, thus saves time. Function call is replaced by function definition by the compiler. b) (i) Function1 is called automatically, when the scope of an object gets over. It is known as Destructor. [ ½ + ½ ] ii) Function4 will be called on execution of statement written as Statement 2. It is Copy Constructor. [ ½ + ½] c) class Stock int ICode; char Item[10]; 2
; float price; int Qty; float Discount ; void FindDisc( ) if (Qty<=50) Discount=0 ; else if(qty>=51 && Qty<=100) Discount=5 ; else if(qty>100) Discount=10; public: Stock() ICode=0; Price=0.0; Qty=0; strcpy(item, NULL ); void Buy( ) cout << Enter item code : ; cin >> ICode; cout << Enter item name : ; gets(item); cout << Enter price : ; cin >>price; cout << Enter quantity : cin >> Qty; FindDisc( ); void ShowAll( ) cout<< Item Code : <<ICode; cout<< Item Name : ;puts(item); cout<< Price : <<price; cout<< Quantity: <<Qty; cout<< Discount: << Discount; d) (i) Multiple inheritance [1] (ii) Register(), Input(), Output(), Sitein(), Siteout() [1] (iii) Data members: None [1] 3
(iv) Member Function: Register(), Show() Function Output( ) is not accessible inside the function SiteOut( ). Online and FacetoFace classes are independent classes. [1] But after inheriting Output () is accessible inside function SiteOut() as both are member functions of the same class. Ques. 3 a) void SumUnit2(int A[ ],int size) [3] int S=0,i; for(i=0;i<size;i++) if((a[i]%10)%2==0) S+=A[i]; cout<<s; [3] b) Formula for column major: Address of T[i][j]=B+W*((i-i r )+(j-j r )*R) As per question: 9800=b+4*(25+50*10) or, b=9800-4*525 or, b=9800-2100=7700 Therefore base address is 7700. Therefore, address of T[30[15]=7700+4*(30+15*50) = 7700+4*(30+750) = 7700+4*780=7700+3120=10820 c) void remove(book *front) [4] BOOK *Temp; If(front==NULL) cout<< Queue underflow. ; else Temp=front; 4
cout<<element removed : << Temp->bprice; if(front->link==null) front=null; else front=front->link; \\Output; for(temp=front; temp->link!=null; temp=temp->link) cout<< temp->bprice; cout<< temp->bprice; d) int sum(int B[ ][3], int r, int c) int count=0,i,j,s=0; for(i=0;i<r;i++) for(j=0;j<c;j++) if(count%2==0) s+=b[i][j]; count++; return count; e) [2] Scanned element Operation Stack Intermediate Result True Push True False Push True, False NOT Pop one ele and True, True NOT(False)=True push result OR Pop two ele and push result True True OR True= True False Push True, False 5
True Push True, False, True OR Pop two ele and push result True, True AND Pop two ele and True push result False OR True True AND True Ques. 4. a) [1] #include<fstream.h> class Employee int Eno; char Ename[30]; public: //Function to count the total number of records int Countrec( ); ; int Employee:: Countrec( ) fstream File; File.open( Emp.Dat,ios::binary ios::in); File.seekg(0,ios::end) // Statement 1 int Bytes = File.tellg() // Statement 2 int count = Bytes/sizeof(Employee); File.close( ); return count; 6
b) [2] void COUNT(void) ifstream fin; char wd[10]; int c=0; fin.open( coordinate.txt, ios::in); while(!fin.eof()) fin>>wd; if(isupper(wd[0])) c++; cout<< No. of words with first capital letter : <<c; fin.close(); c) [3] void TRANSFER( ) ifstream fin; ofstream fout; Phonlist P; fin.open( PHONE.DAT,ios::in); fout.open( PHONBACK.DAT,ios::out); while(!fin.eof()) fin.read((char *)&P,sizeof(P)); if(p.checkcode( DEL )==0) fout.write((char *)&P,sizeof(P)); fin.close(); fout.close(); 7
Ques. 5 a) [2] DDL (Data Definition Language) commands are commands used for defining the data structures specially database schemas. Example: CREATE, ALTER, DROP DML(Data Manipulation Language) commands are used for data manipulation. Example: SELECT, UPDATE, DELETE, INSERT b) [6] (i) SELECT * FROM CONSUMER WHERE ADDRESS = DELHI ; (ii) SELECT * FROM STATIONARY WHERE PRICE>=8 AND PRICE <=15; (iii) SELECT CONSUMERNAME, ADDRESS, COMPANY, PRICE FROM CONSUMER C, STATIONARY S WHERE S.S_ID=C.S_ID; (iv) UPDATE STATIONARY SET PRICE=PRICE+2; (v) DISCTINCT ADDRESS Delhi Mumbai Banglore (vi) Company MAX(Price) MIN(Price) COUNT(*) ABC 15 10 2 XYZ 7 6 2 CAM 5 5 1 8 (vii) (viii) Consumer.ConsumerName Stationary.StationaryName Stationary.Price Good Learner Pencil 5 Write Well Gel Pen 15 Topper Dot Pen 10 Write & Draw Pencil 6 Motivation Pencil 5 StationaryName Price*3 Dot Pen 30 Pencil 18 Eraser 21 Pencil 15 Gel Pen 45
Ques.6 a) LHS : [2] (A +B ).(A+B) = A.A + A.B +B.A+B.B = 0+ A.B+A.B +0 = A.B+A.B = RHS b) A.(B+C ) [2] c) [1] Canonical SOP form: (0,2,4,5) = F(X,Y,Z)=X Y Z +X YZ +XY Z +XY Z d) [3] Octet-1 (m 0 +m 1 +m 4 +m 5 +m 12 +m 13 +m 8 +m 9 ) = c Octet-2 (m 1 +m 3 +m 5 +m 7 +m 13 +m 15 +m 9 +m 11 ) = d Therefore, reduced expression using K-map is (c +d) Ques.7 a) [2] Message switching technique Packet switching technique 1.No limit on block size 1. Tight upper limit on block size 2. Data packets are stored on the disk 2.Packets are stored in main memory 3.Throughput is less improved in 3.Throughput is more improved in comparison to packet switching comparison to message switching b) ii) Mbps(Mega bits per second) [1] c) [1] 9
(i) (ii) FTP- File Transfer Protocol (ii) GSM- Global System for Mobile communication d) (i) ii) The most suitable building to house the server will be Training Building as it contains maximum number of computers and as per 80-20 rule that states that 80% of traffic must be local. iii) i. Repeater will be placed between Training Building & Accounts Building as the distance between them is more than 100m. ii. Hub/Switch in every building to connect computers in each building iv) The NGO is planning to connect its International office situated in Delhi. Optical Fibre will be better for very high speed connectivity. e) A Trojan horse is a computer program which carries out malicious operations without the user s knowledge. It is a piece of harmful code placed within a healthy program which destroys files. [1] f) [1] STAR Topology Requires more cable length than bus topology Difficult to expand BUS Topology Requires less cable length than star topology Easy to expand -----------------------XXXXX----------------------- 10