FRIEND FUNCTIONS
·
The
private members cannot be accessed from outside the class. (i.e.) a non-member
function cannot have an access to the private data of a class.
·
It is
a non-member function but can have access to the member of class through
objects.
·
To
make a non-member can have access to the members of a class declare it inside
the class using the keyword friend.
Syntax
Class class-name
{
Friend return-type
fun-name(objects);
}
Example
#include<iostream.h>
#include<conio.h>
class sample
{
int a;
public:
void get(int x1)
{
a=x1;
}
friend int cube(sample s);
};
int cube(sample s)
{
return(s.a*s.a*s.a);
}
void main()
{
sample x;
int a;
cout<<"Enter a value=";
cin>>a;
x.get(a);
cout<<"\n Cube="<<cube(x);
getch();
}
OPERATOR
OVERLOADING
In c++, we can
overload most operators so that they perform special operations relative to
classes that we create
Syntax
Returntype
classname :: operator op(ar-list)
{
Function body
}
Types of Operator Overloading
Unary Operator Overloading
In unary Operator Overloading argument list will be
empty.
#include<iostream.h>
#include<conio.h>
class simple
{
int x,y,z;
public:
void getdata(int a,int b,int c);
void display(void);
void operator-();
};
void simple :: getdata(int a,int b,int c)
{
x=a;
y=b;
z=c;
}
void simple :: display()
{
cout<<x<<" ";
cout<<y<<" ";
cout<<z<<" ";
cout<<"\n";
}
void simple :: operator-()
{
x=-x;
y=-y;
z=-z;
}
void main()
{
simple s;
clrscr();
s.getdata(10,20,30);
s.display();
-s;
s.display();
getch();
}
Binary Operator Overloading
In binary operator
overloading argument list will contain one parameter and one return object.
#include<iostream.h>
#include<conio.h>
class sum
{
int x,y;
public:
sum()
{
}
sum(int a,int b)
{
x=a;
y=b;
}
void display();
sum operator+(sum);
};
sum sum :: operator+(sum x1)
{
sum g;
g.x=x+x1.x;
g.y=y+x1.y;
return(g);
}
void sum :: display()
{
cout<<"\n X="<<x;
cout<<"\n Y="<<y;
}
void main()
{
sum s1(10,20);
sum s2(20,20);
clrscr();
sum s3;
cout<<"\n S1 Value";
s1.display();
cout<<"\n S2 Value";
s2.display();
s3=s1+s2;
cout<<"\n S3 Value";
s3.display();
getch();
}
TEMPLATES
Z
It
enables us to define generic classes and functions and thus provides support
for generic programming.
Z
A
template can be used to create a family of classes or functions.
Z
It can
be used considered as a king of macro. When an object of a specific type is
defined for actual use, the template definition for that class is substituted
with the required data type.
Z
Since
a template is defined with a parameter that would be replaces by a specified
data type at the time of actual use of the class or function, the templates are
sometimes called parameterized classes or functions
Example
Class Template
#include<iostream.h>
#include<conio.h>
template<class gp>
class add
{
gp a,b,c;
public:
add(gp x,gp y)
{
a=x;
b=y;
}
void sum()
{
c=a+b;
cout<<"\n a="<<a;
cout<<"\n b="<<b;
cout<<"\n c="<<c;
}
};
void main()
{
clrscr();
add<int>a1(10,20);
add<float>a2(3.5,3.2);
a1.sum();
a2.sum();
getch();
}
Function Template
#include<iostream.h>
#include<conio.h>
template<class T>
void swap(T &x,T &y)
{
cT t=x;
x=y;
y=t;
}
void main()
{
int m,n;
float a,b;
clrscr();
cout<<"Enter the value of m and n=";
cin>>m>>n;
cout<<"\nEnter the value of a and b=";
cin>>a>>b;
cout<<"\n Before Swapping";
cout<<"\n M="<<m;
cout<<"\n N="<<n;
swap(m,n);
cout<<"\n After Swapping";
cout<<"\n M="<<m;
cout<<"\n N="<<n;
cout<<"\n Before Swapping";
cout<<"\n A="<<a;
cout<<"\n B="<<b;
swap(a,b);
cout<<"\n After Swapping";
cout<<"\n A="<<a;
cout<<"\n B="<<b;
getch();
}
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