c++ 类的数据成员初始化

class First{
public:
	int num = 0;//错误
	const int num1 = 0;//错误
	static int num2 = 0;//错误
	static const int num3 = 0;//正确，只有静态常量整型数据成员才可以在类中初始化
	string str = "0";//错误
	const string str1 = "0";//错误
	static string str2 = "0";//错误
	static const string str3 = "0";//错误
	float fnum = 0;//错误
	const float fnum1 = 0;//错误
	static float fnum2 = 0;//错误
	static const float fnum3 = 0;//错误
};