#include<iostream> 		//pgm on employee using files
#include<string.h>
#include<fstream>
using namespace std;
class employee
{
	int no;
	char name[20],des[20],dep[20];
	float sal;
	public:
		void input()
		{
			cout<<"\nEnter employee no., name, designation, department and salary: ";
			cin>>no>>name>>des>>dep>>sal;
		}
		void display()
		{
			cout<<no<<"\t"<<name<<"\t"<<des<<"\t\t"<<dep<<"\t"<<sal<<"\n";
		}
		char* getdep()
		{
			return dep;
		}
		int getno()
		{
			return no;
		}
		char* getdes()
		{
			return des;
		}
		void modsal()
		{
			cout<<"\nEnter salary: ";
			cin>>sal;
		}
};
int main()
{
	int opt, n, i, j, empno, flag=0;
	employee e, t[10], temp;
	char ch, d[20];
	cout<<"\nEnter number of employees: ";
	cin>>n;
	fstream f;
	f.open("Employee.dat",ios::out|ios::binary);
	for(i=0;i<n;i++)
	{
		e.input();
		f.write((char*)&e,sizeof(e));
	}
	f.close();
	do
	{
		cout<<"\n1.Search for employee"
			"\n2.display employees in a specific department"
			"\n3.Sort employees according to designation"
			"\n4.Modify salary of an employee"
			"\nEnter choice: ";
		cin>>opt;
		switch(opt)
		{
			case 1:
				cout<<"\nEnter employee no.: ";
				cin>>empno;
				f.open("Employee.dat",ios::in|ios::binary);
				for(i=0;i<n;i++)
				{
					f.read((char*)&e,sizeof(e));
					if(empno==e.getno())
					{
						flag=1;
						cout<<"\nE.no\tName\tDesignation\tDepartment\tSalary\n";
						e.display();
						break;
					}
				}
				f.close();
				if(flag==0)
					cout<<"\nRecord not found!!";
				break;
			case 2:
				cout<<"\nEnter department: ";
				cin>>d;
				f.open("Employee.dat",ios::in|ios::binary);
				for(i=0;i<n;i++)
				{
					f.read((char*)&e,sizeof(e));
					if(strcmp(d,e.getdep())==0)
					{
						flag=1;
						e.display();
					}
				}
				f.close();
				if(flag==0)
					cout<<"\nRecord not found!!";
				break;
			case 3:
				f.open("Employee.dat",ios::in|ios::binary);
				for(i=0;i<n;i++)
				{
					f.read((char*)&e,sizeof(e));
					t[i]=e;
				}
				for(i=0;i<n;i++)
					for(j=0;j<n-1-i;j++)
				  		if(strcmp(t[j].getdes(),t[j+1].getdes())>0)
				 		{
				 			temp=t[j];
				 			t[j]=t[j+1];
				 			t[j+1]=temp;
				 		}
				cout<<"\nE.no\tName\tDesignation\tDepartment\tSalary\n";
				for(i=0;i<n;i++)
					t[i].display();
				f.close();
				break;
			case 4:
				cout<<"\nEnter employee no.: ";
				cin>>empno;
				f.open("Employee.dat",ios::in|ios::out|ios::binary);
				for(i=0;i<n;i++)
				{
					f.read((char*)&e,sizeof(e));
					if(empno==e.getno())
					{
						e.modsal();
						f.write((char*)&e,sizeof(e));
						cout<<"\nE.no\tName\tDesignation\tDepartment\tSalary\n";
						e.display();
						break;
					}
				}
				f.close();
				break;
			default: cout<<"\nInvalid option!";
		}
		cout<<"\nDo you want to continue?[y/n]: ";
		cin>>ch;
	}
	while(ch=='y');
}