Hi, everyone What's the mechanism or grammar for the next code to work? The testFunc() function receives object D as a factor, and it works even if you insert object C pointer.
#include <iostream>
class C
{
public:
C (){}
};
struct D
{
protected:
C *node_{nullptr};
public:
D() = default;
D(C *c) { node_ = c;};
};
void testFunc(D input){
std::cout << "Hello, World!" << std::endl;
}
int main() {
C* c = new C();
testFunc(c);
return 0;
}
Because the D class has a constructor named D:D(C*), an instance of D is created to receive C* and the function is called.
This constructor allows the following code:
D d = new C;
These constructors are called conversion constructors because they appear to convert to different types.
Use explicit to prevent this implicit generation.
explicit D(C *c) { node_ = c;}
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