This document discusses objects as function arguments and static class members in C++. It explains that objects can be passed to functions by value or reference, and the differences between the two. It also describes how static class members, including variables and functions, work. Static members are shared across all objects of a class and can be accessed directly via the class name, unlike non-static members which require an object instance. An example class demonstrating static and non-static members and functions is provided.

1. 29
Objects As Function
Arguments• Like any other variable, objects can also be
passed to the function, as an argument
• There are two ways of doing this
– Pass by value
– Pass by reference
• In the pass by value, the copy of the object is
passed to the function
• So, the changes made to the object inside
the function do not affect the actual object

2. 30
Contd…..
• On the other hand, address of the object is
passed in the case of pass by reference
• So the changes made to the object inside
the function are reflected in the actual
object
• This method is considered more efficient

3. 31
• Eg:
class height
{
int feet, inches; public:
void get_height()
{
cout<<“Enter height in feet and
inches”;
cin>>feet>>inches;
}
void put_height()
{
cout<<Feet:<<feet; cout<<and
inches:<<inches;
}
void sum(height, height);
};
void height:: sum(height h1, height
h2)
{
inches= h1.inches+h2.inches;
feet=inches/12; inches=inches%12;
feet=feet+h1.feet+h2.feet;
}
int main()
{
height h1, h2, h3; h1.get_height();
h2.get_height();
h3.sum(h1, h2);
cout<<“Height :”<<h .put_height();ϭ ϭ

4. 32
Static Data Members
• Each object of a class maintain their own
copy of data member
• However, in some cases, it may be necessary
that all objects of a class have access to the
same copy of a single variable.
• This can be made possible by using static
variable
• A static variable is declared using the static
keyword

5. 33
Contd…
• Only one copy of static member is created for
the entire class and is shared by all the
objects of that class, no matter how many
objects are created
• It is visible only within the class, but its
lifetime is the entire program
• It is initialized to zero when the first object of
its class is created
• It is also known as class variable

6. 34
• Eg:
class A
{
static int
count; int
variable;
public:
A()
{
count++;
}
void get_var()
{
cin>>variable;
}
void put_var()
{
cout<<variable;
}
void put_count()
{
cout<<count;
}
};
int A:: count; // the type and
scope of each static member
variable is defined outside class
definition
main()
{
A a, b, c; a.put_count();
b.put_count(); c.put_count();
return(0);
}
Output: 1 2 3

7. 35
Static Member Function
• In a class, functions can also be declared as
static
• Properties of static functions are:
– They can access only other STATIC
members(functions or variables) declared in the
same class
– They can be called using class name ( instead of
its object)
– Eg: class_name::function_name

8. class A
{
int no;
static int count; //static member
public:
void set_no()
{
count++;
no=count;
}
void put_no()
{
}
static void put_count() //static member
function accessing static member
{
}
};
Int A::count;
main()
{
A a1, a2;
a1.set_no();
a2.set_no();
A::put_count();
a1.set_no();
a2.set_no();
A::put_count();
a1.put_no();
a2.put_no();
return(0);
} 40

9. THE
END
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