C++

Forum

 
Direct vs Copy initialisation with explicit copy constructor. Why we get the following error ?

kapil2905 (146)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
 
class K {
  public:
    int x_;
    explicit K(int x) : x_{x} {}
    explicit K(const K& k) : x_{k.x_} {}  // No error is seen if this is made
};                                        // non explicit.

K factory_function(int x) {
  return K{x};
}

int main() {
  K k1{factory_function(20)};   // [1] works fine with explicit copy constructor.
  K k2 = factory_function(30);  // [2] gives error with explicit copy constructor.
  return 0;
}



r1.cc: In function ‘K factory_function(int)’:
r1.cc:54:13: error: no matching function for call to ‘K::K(K)’
   return K{x};
             ^
r1.cc: In function ‘int main()’:
r1.cc:59:29: error: no matching function for call to ‘K::K(K)’
   K k2 = factory_function(30);


factory_function() returns an object of type "K" ==> Does [2] still requires conversion ?

It'll be really helpful if I can get a detailed answer on where copy/conversion is needed and why it works if we make copy constructor non explicit.

Thanks for any help :)
Last edited on
JLBorges (13770)
Topic archived. No new replies allowed.