Page 117 - C++

public:
void EnterData() {cin>>Rno; cin.getline(Name,20);
void ShowData() {cout<<Rno<<” - ”<<Name<<endl;}
};
With reference to this information, write output of the following program segment:
ifstream File; Student S;
File.open(“STUDENTS.DAT”,ios::binary|ios::in);
File.seekg(0, ios::end);
Cout<<File.tellg();

Ans: 220 because total 10 records each of 22 bytes , when open a file in reading mode the file pointer
th
comes to 0 byte and ios::end will take the pointer to the end and will return the byte no. at end.

(b) Write a function in C++ to count the number of lines starting with a digit in a text file “DIARY.TXT”.
Ans:
void abc()
{ int c=0;
char line[80];
ifstream fin(“diary.txt”);
if(!fin) {cout<<”sorry”;exit(0);}
while(!fin.eof())
{
fin.getline(line,80);
if(isdigit(line[0]);
c++;
}
fin.close();
}

(c) Given a binary file “STUDENT.DAT”, containing records of the following class Student type:
class student
{ char S_admno[10]; //Admission no. of student
char S_Name[20]; //Name of student
int Percentage; //Marks percentage of student
public:
void EnterData()
{ gets(S_admno); gets(S_Name); cin>>Percentage;
}
void DisplayData()
{ cout<<setw(12)<<S_admno;
cout<<setw(32)<<S_Name;
cout<<setw(3)<<Percentage<<endl;
}
int Ret_Per() {return Percentage;}
};
Write a function in C++ that would read contents of the file “STUDENT.DAT” and display the details of
those students whose percentage is above 75.
Ans:
void read()
{ student s1;
ifstream fin(“student.dat”, ios::binary);
if(!fin) {cout<<”sorry”;exit(0);}
while(!fin.eof())
{ fin.read((char*)&s1, sizeof(s1));
if(s1.ret_per()>75)