About basics of Function overloading and Operator overloading

2. In C++, two or more functions can share
the same name as long as their parameter
declarations are different.
In this situation, the functions that share
the same name are said to be overloaded,
and the process is referred to as function
overloading

3. To see why function overloading is important,
first consider three functions defined by the
C subset: abs(), labs(), and fabs().
abs() returns the absolute value of an integer,
labs() returns the absolute value of a long,
and
fabs() returns the absolute value of a double.

4. Although these functions perform almost
identical actions, in C three slightly
different names must be used to represent
these essentially similar tasks.
Example: Function Overloading

5. Function Overloading – DEFINITION
It is the process of using the same name for
two or more functions.
The secret to overloading is that each
redefinition of the function must use
either-
• different types of parameters
• different number of parameters.

6. The key to function overloading is a function’s
argument list.
A function’s argument list is known as its signature.
Example :
Different types of Different number of parameters
arguments
void print(int a); void area(float r);
void print (double b); void area(float l, float b);
void print(char c); void area(float a, float b, float c);

7. If two function have same number and
types of arguments in the same order, they
are said to have the same signature.
There is no importance to their variable
names.
• void print(int x, float y);
• void print(int p, float q); are said to
have same signature.

8. Calling Overloaded Function
Overloaded functions are called just like
ordinary functions.
The signature determines which function
among the overloaded functions should be
executed.
print(3);
print(‘B’);

9. STEPS FOR FINDING BEST MATCH
The actual arguments are compared with
formal arguments of the overloaded
functions and the best match is found
through a number of steps.
In order to find the best match, the
compiler follows the steps given below:

10. STEPS - 1 : Search for an exact match
If the type of the actual and formal
argument is exactly the same, the compiler
invokes that function.
void print(int x); // function #1
void print(float p); // function #2
void print(char c); // function #3
------------
-------------
print(5.3); //invokes the function #2

11. STEPS - 2 : A match through promotion
If no exact match is found, an attempt is
made to achieve a match through
promotion.
void print(int x); // function #1
void print(float p); // function #2
void print(double f); // function #3
------------
-------------
print(‘c’); //matches the function #1
through promotion

12. STEPS - 3 : A match through standard
C++ conversion rules
If the first and second steps fail, then an
attempt is made to find a best match
through conversion rule.
void print(char x); // function #1
void print(float p); // function #2
------------
-------------
print(342); //matches the function #2
int 342 is converted to float

13. STEPS - 4 : A match through user
defined conversion
If all the above three steps fail to find a
match, then an attempt is made to find a
match by applying user defined
conversion rules.

14. Constructor Overloading
Just like any other function, constructors
can also be overloaded.
We can use constructor overloading for
initializing the objects based on different
conditions.

15. In Constructor Overloading, we need not
call the constructor separately because
they are invoked automatically.
But
In Function Overloading, we have to invoke
them separately.

16. Functions with Default Arguments
Vs
Overloading
Functions with default arguments can be
called with optional number of arguments
and hence it gives an appearance of
function overloading.
float calc(float p, int q=8, float r=18.3);
-------------------
float f = calc(3.5);
float f = calc(3.5, 10);

18. It is one type of Static Polymorphism.
C++ has about 45 operators. These operators
are defined for the fundamental data types
(int, float etc).
While defining a class, we are actually creating
a new datatype.
Most of the C++ operators can be overloaded
to apply to our new class datatype.

19. Operator overloading is the
concept of giving new meaning to
an existing C++ operator.
• When overloaded, the operators are
implemented as functions using the operator
keyword.
• For example, the syntax of overloading the
addition operator “+” would be operator+().

20. One of the nice features of C++ is
that you can give special meanings
to operators, when they are used
with user-defined classes. This is
called operator overloading.

21. You can implement C++ operator
overloads by providing special
member-functions on your classes that
follow a particular naming convention.
For example, to overload the +
operator for your class, you would
provide a member-function named
operator+ on your class.

22. 1. Read the following function definition :
void print(int x)
{
cout << x;
}
void print (float x)
{
cout << x;
}
void print(char x)
{
cout << x;
}

23. a. All these functions can be used in the same
program. Explain this feature of C++
b. Write sample statements to invoke each of
these functions.
a) About FUNCTION OVERLOADING
b) print(35); print(32.7); print(‘M’);

24. 2. Function with default arguments performs
overloading. Explain this fact with the help
of example.
• Functions with default arguments can be
called with optional number of arguments
and hence it gives an appearance of function
overloading.
float calc(float p, int q=8, float r=18.3);
-------------------
float f = calc(3.5);
float f = calc(3.5, 10);

25. 3. Why is function overloading connected to
compile-time polymorphism or early
binding?
• Early binding refers to the ability of the
compiler to relate or bind a function call with
the function definition during compilation
itself. FUNCTION OVERLOADING comes under
this category because it match the actual
arguments with formal arguments during
compile-time.