c++ class member initializer list

class Test  {
private:
  std::string data;
public:
  test(std::string data) : data(data) {}
  std::string getData() {
    return data;
  }
};

int main() {
  Test test("This is just some random Text");
  std::cout << test.getData() << std::endl;
  return 0;
}

#include <iostream>
class Entity {
private : 
	std::string m_Name;
	int m_Score;
	int x, y, z;
public:
	Entity()
		:m_Name("[Unknown]"),m_Score(0),x(0),y(0),z(0)//initialize in the order of how var are declared
	{
	}
	Entity (const std::string& name) 
		:m_Name(name)
	{}
	const std::string& GetName() const { return m_Name; };
};
int main()
{
	Entity e1;
	std::cout << e1.GetName() << std::endl;
	Entity e2("Caleb");
	std::cout << e2.GetName() << std::endl;
	std::cin.get();
}