Some doubts about inheritance

[Maerle]

#include <iostream>
#include <conio.h>
using namespace std;

class C1 {
	protected:
		float m_c1;
	public:
		C1(float x) { m_c1 = x; }
		void print() { cout << "C1:" << m_c1 << endl; }
};
class C2 : public C1 {
	protected:
		float m_c2;
	public:
		C2(float x) : C1(1) { m_c2 = x; }
		void print() { cout << "C2:" << m_c1 + m_c1 << endl; }
};
class C3 : public C2 {
	protected:
		float m_c3;
	public:
		C3(float x) : C2(2) { m_c3 = x; }
		void print() { cout << "C3:" << m_c1 + m_c2 + m_c3 << endl; }
};

int main()
{
	C1 c1(2.3);
	C2 c2(5.7);
	C3 c3(1.9);
	c1.print();
	c2.print();
	c3.print();
	getch();
	return 0;
}

1) Why does the function 'c1.print();' prints '2.3' instead of '1', if the fuction 'c2.print();' prints '2' and 'function 'c3.print(); prints '4.9'.

[moorecm]

1) C1 prints whatever it is constructed with.

2) Inspect lines 16 and 17 very closely. Line 16 invokes the base constructor C1 with a value of 1. Line 17 is printing m_c1 + m_c1, which is 1 + 1.

3) Similarly, in C3, m_c1 is 1, m_c2 is 2, and m_c3 is 1.9, totaling 4.9.

[Maerle]

I think I understod, but line 23 doesn't invokes the base constructor C1. Or not?

[moorecm]

It does. C3 inherits from C2, which inherits from C1. The constructors are called in order from the base class up to the most derived subclass.