I wrote those two overloads:
int func(int, int) { return 1; } int func(double, double) { return 2; }
When I call them with the obvious two calling schemes, i.e. func(1, 1)
and func(1.0, 1.0)
, the first and the second overloaded functions are called, respectively, and when I try to call func(1, 1.0)
it gives me an error, but when I cast the 1
to a long long
, I don't get an error, and the second overload is the one called.
#include <iostream> int main() { std::cout << func(1, 1); // outputs 1. std::cout << func(1.0, 1.0); // outputs 2. // std::cout << func(1, 1.0); // erroneous. std::cout << func((long long)1, 1.0); // outputs 2. }
Why is this the case? At first, I thought it was because of some promotion, but I tried a third overload with two floats and I could not get it to be called by calling it like func((int)1, 1.0f)
. I don't know why wouldn't it be the same, and I don't know why the second overload was called when a long long
was passed.
In Java, function overloading is also known as compile-time polymorphism and static polymorphism.
Function Overloading is when multiple function with same name exist in a class. Function Overriding is when function have same prototype in base class as well as derived class. 2. Function Overloading can occur without inheritance.
C++ lets you specify more than one function of the same name in the same scope. These functions are called overloaded functions, or overloads. Overloaded functions enable you to supply different semantics for a function, depending on the types and number of its arguments.
Function overloading is a C++ programming feature that allows us to have more than one function having same name but different parameter list, when I say parameter list, it means the data type and sequence of the parameters, for example the parameters list of a function myfuncn(int a, float b) is (int, float) which is ...
No, not with the overloaded lt function as written, which assumes that both arguments are Rectangle objects. The following error message would be generated: Undefined function 'rectarea' for input arguments of type 'double'. However, it is possible to rewrite the function to handle this case.
The return type of all these functions is the same but that need not be the case for function overloading. Note: In C++, many standard library functions are overloaded. For example, the sqrt () function can take double, float, int, etc. as parameters. This is possible because the sqrt () function is overloaded in C++.
In this tutorial, we will learn about the function overloading in C++ with examples. In C++, two functions can have the same name if the number and/or type of arguments passed is different. These functions having the same name but different arguments are known as overloaded functions.
Which function from an overload set is chosen to be called (i.e. overload resolution) depends (in part) on how many arguments of the function call must go through an implicit conversion, and what kind of conversion is needed.
Which function from an overload set is chosen to be called (i.e. overload resolution) depends (in part) on how many arguments of the function call must go through an implicit conversion, and what kind of conversion is needed.
The rules that are relevant to your example are:
For each pair of viable function F1 and F2, the implicit conversion sequences from the i-th argument to i-th parameter are ranked to determine which one is better.
F1 is determined to be a better function than F2 if implicit conversions for all arguments of F1 are not worse than the implicit conversions for all arguments of F2, and ... there is at least one argument of F1 whose implicit conversion is better than the corresponding implicit conversion for that argument of F2.
So given the overload set:
int func(int, int); // #1 int func(double, double); // #2
Let's consider the following calls:
func(1, 1); // perfect match for #1, so #1 is chosen func(1., 1.); // perfect match for #2, so #2 is chosen func(1., 1); // could call #1 by converting 1st argument to int // (floating-integral conversion) // could call #2 by converting 2nd argument to double // (floating-integral conversion) // error: ambiguous (equal number of conversions needed for both #1 and #2) func(1ll, 1.); // could call #1 by converting both arguments to ints // (integral conversion for 1st argument, floating-integral conversion for 2nd argument) // could call #2 by converting just 1st argument to double // (floating-integral conversion for 1st argument) // for the 2nd parameter, #2 is ranked as a better choice, // since it has a better implicit conversion sequence for #2 // and so #2 is chosen (even though both #1 and #2 are tied for the 1st argument)
Now let's add a third overload into the mix:
int func(float, float); // #3
Now when you make the call:
func(1, 1.f); // could call #1 by converting 2nd argument to int // (floating-integral conversion for 2nd argument) // could call #2 by converting 1st argument to double, and converting 2nd argument to double // (floating-integral conversion for 1st argument, and floating-point promotion for 2nd argument) // could call #3 by converting 1st argument to float // (floating-integral conversion for 1st argument) // error: ambiguous (equal number of conversions needed for #1, #2 and #3)
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