Question

I was trying out default argument values and function overloading in c++ by compiling the following code and I was surprised by the output which was :

Line 19: error: call of overloaded 'add()' is ambiguous

The code I compiled is :

#include <iostream>

using namespace std;

void add(int a=1, int b=1){

cout<<a+b;
}

void add(){

int a =2, b=2;
cout<<a+b;
}


int main(){

add();

return 0;
}

Any explanations why it is ambiguous? Thx in advance.

Answer 1

Because both signatures match the call.

add();

can be interpreted as either add(1,1) or add(). When you write void add(int a=1, int b=1), you’re telling the compiler – “Listen dude, if I call add with no parameters, I want you to default them to 1“

Most importantly, what do YOU expect to happen when you call add() with no parameters?

• If you expect it to print 2, remove the version that takes no parameters.

• If you expect it to print 4, remove the default parameters from the first version.