Objects as Function Parameter & ReturnType

1. Objects as Function
Parameters & Return Type
Muhammad Hammad Waseem
m.hammad.wasim@gmail.com

2. Object as Function Parameters
• Objects can also be passed as parameters to member functions.
• The method of passing objects to a functions as parameters is as
passing other simple variables.
• It will easily be understand by following example.

3. Example
class Travel
{
private:
int km, hr;
public:
Travel() { km=hr=0; }
void get() {
cout<<“Enter Kilometers traveled”;cin>>km;
cout<<“Enter Hours traveled”;cin>>hr;
}
void show() {
cout<<“You traveled ”<<km<<“ in ”<<hr<<“
hours”<<endl;
}
void add(Travel p) {
Travel t; t.km=km+p.km; t.hr=hr+p.hr;
cout<<“Total traveling is ”<<t.km<<“ kilometers in
”<<t.hr<<“ hours”<<endl;
}
};
void main()
{
Travel my, your;
my.get(); my.show();
your.get(); your.show();
my.add(your);
getch();
}

4. How Program Works
• The above program declares to objects of class Travel and inputs data in both objects.
• The add() function accepts an object of type Travel as parameter.
• It adds the values of data members of the parameter object and the values of calling object’s data
members and displays the result.
• The working of member function add() is as follows:
void add(Travel p) {
Travel t;
t.km = km + p.km;
t.hr = hr + p.hr;
}
• Data members of temporary object t
• Data members of temporary object my
• Data members of temporary object p
Function call in main
my.add(your);

5. Returning Objects from Member Function
• The method of returning an object from member function is same as
returning a simple variable.
• If a member function returns an object, its return type should be the
same as the type of object to be returned.

6. Example
class Travel
{
private:
int km, hr;
public:
Travel() { km=hr=0; }
void get() {
cout<<“Enter Kilometers traveled”;cin>>km;
cout<<“Enter Hours traveled”;cin>>hr;
}
void show() {
cout<<“You traveled ”<<km<<“ in ”<<hr<<“
hours”<<endl;
}
Travel add(Travel p) {
Travel t; t.km=km+p.km; t.hr=hr+p.hr;
return t;
} };
void main() {
Travel my, your, r;
my.get(); my.show();
your.get(); your.show();
r = my.add(your);
cout<<“Total travelling is as follow:n”;
r.show();
getch();
}

7. How Program Works
• The add() function in the above program accepts a parameter object
of type Travel.
• It adds the contents of parameter and calling object and stores the
result in a temporary object.
• The function then returns the whole object back to main() function
that is stored in r.
• The program finally displays the result using r.show() statement.