CBSE Guess > Papers > Important Questions > Class XII > 2012 > Computer Science > Computer Science Mr. Pradumna Singh

Computer Science- CBSE CLASS XII

Q. 13. Write functions to perform PUSH  & POP operations  in a dynamically allocated stack containing the objects of the following structure:                             For - 4 Marks
   struct NODE
    {  char name[30];
        float fees;
        NODE *next;     };

ANS.:
NODE *top=NULL; //declaring global pointer & initializing  it with NULL
void PUSH( )
{ NODE *p=new NODE; //creating new dynamic list to go on to stack
cout<<”\nEnter Name : “;
gets(p->name);
cout<<”\nEnter Fees : “;
cin>>p->fees;
p->next=NULL:
                   if(top= = NULL)
                   top=p;
                           else
                               { p->next=top;
                                  top=p }
cout<<”\nList inserted on the top of stack successfully…”;
getch( );

}
void POP( )
{ if(top= = NULL)
  cout<<”\nStack Empty”;
 else
  { NODE *temp=top;
     top=top->next;
    delete temp;
    cout<<”\nList deleted from top of stack successfully…”;
    getch( );
   }

}

Q. 14. Consider the class:                             For - 2 Marks
    class QUEUE
    {
     private:
      int data[20],front,rear;
     public:
     QUEUE( )
      { front=rear=-1; }
     void INSQ(int d); //to insert an element into queue
     void DELQ( ); //to delete an element from the queue
     void PRINTQ( ); //to print the current status of queue
      };
Complete the definition of function DELQ( ) of above class.

Ans.:
void QUEUE::DELQ( )
{
if(front<0)
cout<<”\nQueue Empty”;
else
{
cout<<”\n”<<data[front]<<” has been removed from queue”;
for(int i=front;i<rear;i++)
data[i]=data[i+1];
rear--;
  if(rear<0)
  front=-1; }

Q. 15. Evaluate the following postfix notation of expression:                             For - 2 Marks
                            30, 6, 4, +, /, 14, +, 4, *
SOL. (by tabular method):
Steps     INPUT     ACTION          STACK
1             30            Push                   #30
2             6              Push                  #30,6
3             4              Push                  #30,6,4
4             +              Pop 4,6 &
                               Push 6+4=10     #30,10
5             /               Pop 10,30 &
                               Push 30/10=3    #3
6            14             Push                  #3,14
7            +               Pop 14,3 &
                               Push 3+14=17   #17
8            4               Push                  # 17,4
9            *               Pop 4,17 &
                               Push 17*4=68    #68

Q .16. Observe the program segment given below carefully and answer the question that follows :                              For - 1 Marks
class school
{ private :
 char name[25];
int numstu;
public:
  void inschool( );
  void outschool( );
int retnumstu( )
{ return numstu; }
};
void modify(school A)
  { fstream INOUT;
  INOUT.open(“school.dat”,ios::binary|ios::in|ios::ate);
school B;
  int recread=0, found=0;
  while(!found && INOUT.read((char*)&B,sizeof(B))
  { recread++;
if(A.retnumstu( )= = B.retnumstu( ))
  {
    ____________________________//missing statement
                                               
INOUT.write((char*)&A,sizeof(A));
   Found=1;
  }
  else
  INOUT.write((char*)&B,sizeof(B));
   }
   if(!found)
cout<<”\nRecord for modification does not exist”;
INOUT.close( );  

If the function modify( ) is supposed to modify a record in file school.dat with the values of school A passed to its argument, write the appropriate statement for missing statement using seekp( ) or  seekg( ) , whichever needed, in the above code that would write the modified record at its proper place.
Ans. :
INOUT.seekp(-1*sizeof(school),ios::cur);
OR
INOUT.seekg(-1*sizeof(school),ios::cur);

Q. 17. Write a function to count the number of vowels  stored in a text file “STRINGS.TXT”.                             For - 2 Marks

Ans.:
void countvowel( )
{ int c=0;
char ch;
ifstream fin(“STRINGS.TXT”);
while(!fin.eof( ))
{
fin.get(ch);     OR fin>>ch;
if(!fin)
break;
switch(ch)
{
case ‘A’:
case ‘a’:
case ‘E’:
case ‘e’:
case ‘I’:
case ‘i’:
case ‘O’:
case ‘o’:
case ‘U’:
case ‘u’:c++;
}
}
cout<<”\nTotal vowels in the data file is “<<c;fin.close( ); }

Q. 18. Write a function to delete a record on the given model number for a TV from the binary file “TV.DAT” containing the objects of TV (as defined below) :                             For - 4 Marks

class TV
{
long model;
float size;
char brand[30],comp[30];
 public:
long retmodel( )
{ return model; }
void Input( ) {cin>>model>>size; gets(brand); gets(comp); }
void  Output( ) { cout<<model<<size<<brand<<comp<<endl; } };

Ans.:
void DELREC(long m)
{ TV ob;
ifstream fin("TV.DAT",ios::binary);
ofstream fout("temp.dat",ios::app|ios::binary);
int flag=0;
while(!fin.eof()) //for searching record
{ fin.read((char*)&ob,sizeof(TV));
if(!fin)
break;
if(ob.retmodel( )= =m)
{ flag=1;
break; }
}
if(!flag)
{ cout<<"\nRecord does not exist";
getch(); }
else //for deleting record
{ fin.seekg(0);
while(!fin.eof())
{ fin.read((char*)&ob,sizeof(TV));
if(!fin)
break;
if(ob.retmodel( )= =m)
fout.write((char*)&ob,sizeof(ob)); }
remove("TV.DAT");
rename("temp.dat","TV.DAT");
cout<<"\nRECORD DELETED SUCCESSFULLY........";
getch(); }
fin.close();
fout.close();}

Prepared By: Mr. Pradumna Singh
mail to: [email protected]