What is conversion constructor in C++?

Answer 1

In C++, if a class has a constructor which can be called with a single argument, then this constructor becomes conversion constructor because such a constructor allows automatic conversion to the class being constructed.

Example

class Test 
{
 private:
   int x;
 public:
   Test(int i) {x = i;}
   void show() { cout<<" x = "<<x<<endl; }
};

int main()
{
 Test t(200);
 t.show();
 t = 300; // conversion constructor is called here.
 t.show();
}

The above program prints:

x = 200
x = 300

Answer 2

Constructor which is called with single argument used for converting from the type of the argument to the class type is called conversion constructor.