PythonProgramming-Binary-file-handling-2.pptx

Reading/Writing Structure Variable
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
#include<fstream.h>
struct student
{
int rollno;
char name[20];
float marks;
};
void main()
{
fstream fout;
student s1;
char ch = 'y';
clrscr();
fout.open(“student.dat“ , ios::out);
while(ch!='n')
{
cout<<"Enter Roll No.";
cin>>s1.rollno;
cout<<"nEnter Name:";
gets(s1.name)
cout<<"nEnter marks:";
cin>>s1.marks;
fout.write((char *)&s1 , sizeof(s1));
cout<<"nDo you want to add more data:";
cin>>ch;
}
fout.close();
cout<<"nnData in file......";
fout.open("dataread.dat",ios::in);
fout.read((char *)&s1 , sizeof(s1)) ;
while(fout)
{
cout<<"nRollNo: "<<s1.rollno<<"t";
cout<<"Name: "<<s1.name<<"t";
cout<<"Marks: "<<s1.marks;
fout.read((char *)&s1 , sizeof(s1));
}
fout.close();
getch();
}

Reading/Writing class Object
class student
{ int rollno;
char name[20];
float marks;
public:
void getdata();
void showdata();
};
void student::getdata()
{ cout<<"Enter Roll No.";
cin>>rollno;
cout<<"nEnter Name:";
gets(name);
cout<<"nEnter marks:";
cin>>marks; }
void student::showdata()
{
cout<<rollno<<"t"<<name<<"t"<<marks<<"n";
}
void main()
{ fstream sfile;
student s1;
char ch = 'y';
sfile.open("dataread.dat",ios::out);
while(ch!='n')
{
s1.getdata();
sfile.write((char *)&s1 , sizeof(s1));
cout<<"nDo you want to add more data:";
cin>>ch;
}
sfile.close();
cout<<"nnData in file......n";
sfile.open("dataread.dat",ios::in);
sfile.read((char *)&s1 , sizeof(s1)) ;
while(sfile)
{
s1.showdata();
sfile.read((char *)&s1 , sizeof(s1));
}
sfile.close();
getch();
}

Q.1- Consider the following class declaration:
class employee
{
int code;
char name[20];
float salary;
public:
void input()
{
cin>>code>>name>>salary;
}
void show()
{
cout<<code<<name<<salary<<endl;
}
float retsal()
{
return salary;
}
};
(i) Write a function to write the objects of employee to a binary file.
(ii) Write a function to read objects of employee from the file and display all the objects
on the screen whose salary is between 10000 and 20000.

Ans.
void writeemp()
{
employee emp;
ofstream fout;
fout.open(“employee.dat”,ios::out);
int n,I;
cout<<“Enter no. of records you want to insert”;
cin>>n;
for(i=1 ; i<=n ; i++)
{
emp.input();
fout.write((char *)&emp , sizeof(emp));
}
fout.close();
}
void readdata()
{
employee emp;
ifstream fin;
float esal;
fin.open(“employee.dat” , ios::in);
if(!fin)
cout<<“file does not exist”;
fin.read((char *)&emp , sizeof(emp));
while(fin)
{
esal = emp.retsal();
if(esal>=10000 && esal<=20000)
{
emp.show();
}
}
fin.close();
}

Q.2- Consider the following class declaration:
class camera
{
long modelno;
float megapixel;
char detail[20];
public:
void enter()
{
cin>>modelno>>megapixel>>detail;
}
void display()
{
cout<<modelno<<megapixel<<detail<<endl;
}
long retModel()
{
return modelno;
}
};
Write a function to search for a camera from binary file “camera.dat”. The user will
enter modelno and this function will search and display the complete detail of camera.

Ans.
void search()
{
camera cam;
ifstream fin;
long cmodel;
cout<<“Enter model of camera to be searched ”;
cin>>cmodel;
fin.open(“camera.dat” , ios::in);
if(!fin)
cout<<“file does not exist”;
fin.read((char *)&cam , sizeof(cam));
while(fin)
{
if(cam.retModel() = = cmodel)
{
cam.display();
}
}
fin.close();
}

PythonProgramming-Binary-file-handling-2.pptx

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