Differences between Function Overloading and Function with Default Argument(s)

Differences between Function Overloading and Function with Default Argument(s)

After having discussion on 'Function overloading' and 'Function with default argument' one may think that, these two are very similar, because in both the occasions functions can be called with an optional number of arguments. This is true but still they are not similar.

            In case of function with default argument you may have choice in using number of arguments while calling a function but still the basic behaviour of the function remains same. Moreover if you wish to skip the first or middle argument in function calling, C++ will make no attempt to interpreter that.  Let’s consider the following function prototype to understand this fact more.

float Amt(float P = 2000, int T = 2, float R = 0.08);

Case 1:

Amt(3);

Suppose here the value 3 you want to send as value for ‘T’, but it is not possible. C++ will assign it to ‘P’ and for rest of the arguments default values will be applicable.

Case 2:

Amt(5000,0.13);

Suppose here you want to skip the middle argument. But C++ will assign 5000 to ‘P’ and 0.13 to ‘T’ and for the last argument default value will be applied.

            Thus by now I think it has become clear that, with default argument C++ expects that only the arguments on the right side can be defaulted.

            However you can overcome all of these limitations very easily by overloading Amt() for various possible combinations of arguments, moreover with function overloading you can make a function working differently depending upon the different argument combinations.

            But, with default argument only one instance of function definition is applicable.