FUNCTION OVERLOADING

FUNCTION OVERLOADING

What is polymorphism?

One of the important features of OOPS is Polymorphism. Polymorphism refers to ‘one name having many forms’ different behavior of an instance depending upon the situation.

In what two ways C++ implement polymorphism?

C++ implements polymorphism through overloaded functions and overloaded operators.

What does overloading mean?

The term overloading means a name having two or more distinct meanings.

Thus an overloaded function refers to a function having(one name and) more than one distinct meanings.

What is an overloaded operator?

Similarly, when two or more distinct meanings are defined for an operator, it is said to be an overloaded operator.

What is static or early binding?

The ability of the compiler to select the appropriate function for a particular call at the compile time itself from a set of overloaded functions that are defined. In other words, the required function gets determined only at compile time.

What is function overloading?

When several function declarations are specified for a single function name in the same scope, the (function) name is said to be overloaded. C++ allows functions to have the same name if it can distinguish them by their number and type of arguments.

Or

A function name having several definitions that are differentiable by the number or types of their arguments is known as overloading of functions.

Eg:

void prnsqr(int i);//overloaded for integer

void prnsqr(char c);// overloaded for character

void prnsqr(float f);//overloaded for float

void prnsqr(double d);//overloaded for double

void prnsqr(int i)

{

cout<<"Integer "<<i<<"\n";

}

void prnsqr(char c)

{

cout<<c<<" is a character "<<"\n";

}

void prnsqr(float f)

{

cout<<" Float "<<f"\n";

}

void prnsqr(double d)

{

cout<<"Double "<<d<<"square is"<<i*i<<"\n";

}

What is the need for function overloading?

Function overloading not only implements polymorphism but also reduces number of comparisons in a program and thereby makes the program run faster.

What is a function’s signature?

A function’s argument list(i.e. number and type of arguments) is known as the function’s signature.

Are functions with same signature and same name but different return types allowed?

No

What are the restrictions on overloaded functions?

·         Any  two functions in a set of overloaded functions must have different argument lists.

·         Overloading functions with argument lists of the same types, based on return type alone is an error.

·         Member functions cannot be overloaded .

·         Typedef declarations do not affect overloading mechanism.

What is argument matching?

Argument matching involves comparing the actual arguments of the call with the formal arguments of each declared instance of the function.

What are the three possible cases a function call may result in?

1)      A match – A match is found for a function call

2)      No match – No match is found for the function call

3)      Ambiguous match – More than one defined instance match for the function call.

Ambiguity between float and double, int and long.

What are the steps followed by compiler in order to find the best possible match?

1)      Search for an exact match

void afunc(int);

void afunc(double);

afunc(13);// exact match. Matches afunc(int)

2)      A match through promotion

 void afunc(int);

void afunc(double);

afunc('c');// match through promotion. Matches afunc(int)

3)      A match through application of standard C++ conversion rules

void afunc(char);

void afunc(double);

afunc(97);// match through standard conversion rules. Matches afunc(char)

4)      A match through application of a user-defined conversion.

SA Qns – P-137

1)      Based on the number and type of arguments, the compiler is able to interpret more than one definition during the compile time.

Steps:

i)                    Looks out for exact match, if not found

ii)                   Looks out for match in promotion , if not found

iii)                 Looks out for promotion through conversion

2)      When the number and type of the  formal and actual arguments are the same, then it is said to be exact match.

Eg:

void fun(int a)

{  }

void main()

{

fun(5);

}

4)

####

91827

5)

i)

void repeat(int x, char c)

{

for(int i=1;i<=x;i++)

cout<<c;

}

void repeat()

{

for(int i=1;i<=12;i++)

cout<<"*";

}

void repeat(int x, char c='*')

{

for(int i=1;i<=x;i++)

cout<<c;

}

void repeat(char c, int x=12)

{

for(int i=1;i<=x;i++)

cout<<c;

}

                Both

             ii)

                               

                Function overloading

                iii)

                Default argument

                iv)

                Neither

iv)                 Function overloading onlye

6)

C++ allows a function to assign a parameter a default value when no argument corresponding to that parameter is specified in a call to that function. The default value is specified in a manner syntactically similar to a variable initialization. 
- For example, this declares MyFunction as taking one int argument with a default value of 0 :

void MyFunction(int i =0)
{
   //…
   //…
}

- Now, this MyFunction() can be called one of the following two ways :

MyFunction(10);   //passing explicit value
MyFunction();   //not passing any value; function will give default value

7)

int N=5;

int sum(int arr[])

{

int total=0;

for(int i=0;i<N;i++)

total+=arr[i];

return total;

}

int sum(int arr[], char ch)

{

int etotal=0,ototal=0;

if(ch=='E')

{for(int i=0;i<N;i++)
  if(arr[i]%2==0)

   etotal+=arr[i];

   return etotal;}

else if(ch=='O')

{for(int i=0;i<N;i++)
   if(arr[i]%2!=0)

   ototal+=arr[i];

   return ototal;}

}