Duplicate copies can be avoided using 'virtual' keyword while making ancestral class...

The example illustrates it better:

#include<iostream.h>
#include<conio.h>
#include<string.h>
#include<stdio.h>
class emp
{private:
char n[25] sex id[10];
public:
void get1()
{cout<<"ENTER NAME EMPLOYEE ID AND SEX(M/F) OF EMPLOYEE ";
cin>>n>>id>>sex;
}
void show1()
{
cout<<"nNAME:"<<n<<"nEMPLOYEE ID:"<<id<<"nSEX:"<<sex;
}
};
class sal:virtual public emp
{
public:
float sal;
void get2()
{cout<<"nEnter Salary of employee :Rs ";
cin>>sal;
}
void show2()
{cout<<"nSalary :"<<sal;
}
};
class incent:virtual public emp
{
public:
float in;
void get3()
{cout<<"nEnter incentives :Rs ";
cin>>in;
}
void show3()
{cout<<"nIncentives :Rs"<<in;
}
};
class tsal:public sal incent
{private:
float t;
public:
void get4()
{get1();
get2();
get3();
}
void show4()
{show1();
show2();
show3();
t sal+in;
cout<<"nTotal salary :Rs"<<t;
}
};
void main()
{clrscr();
tsal t;
t.get4();
t.show4();
getch();
}