- 委托构造
- 继承构造
- 显式虚函数重载
- 显式禁用默认函数
- 强类型枚举
代码语言：javascript
复制#include <iostream>
#include <string>
class Base {
public:
std::string str;
int value;
Base() = delete;
Base(std::string s) {
str = s;
}
// delegate constructor
Base(std::string s, int v) : Base(s) {
value = v;
}
// final constructor
virtual void foo() final {
return;
}
virtual void foo(int v) {
value = v;
}
};
class Subclass final : public Base {
public:
double floating;
Subclass() = delete;
// inherit constructor
Subclass(double f, int v, std::string s) : Base(s, v) {
floating = f;
}
// explifict constructor
virtual void foo(int v) override {
std::cout << v << std::endl;
value = v;
}
}; // legal final
// class Subclass2 : Subclass {
// }; // illegal, Subclass has final
// class Subclass3 : Base {
// void foo(); // illegal, foo has final
// }
int main() {
// Subclass oops; // illegal, default constructor has deleted
Subclass s(1.2, 3, "abc");
s.foo(1);
std::cout << s.floating << std::endl;
std::cout << s.value << std::endl;
std::cout << s.str << std::endl;
}
代码语言：javascript
复制#include <iostream>
template<typename T>
std::ostream& operator<<(typename std::enable_if<std::is_enum<T>::value, std::ostream>::type& stream, const T& e)
{
return stream << static_cast<typename std::underlying_type<T>::type>(e);
}
// there will be compile error if all define value1 u548c value2
enum Left {
left_value1 = 1,
left_value2
};
enum Right {
right_value1 = 1,
right_value2
};
enum class new_enum : unsigned int{
value1,
value2,
value3 = 100,
value4 = 100
};
int main() {
if (Left::left_value1 == Right::right_value2) {
std::cout << "Left::value1 == Right::value2" << std::endl;
}
// compile error
// if(new_enum::left_value1 == 1) {
// std::cout << "true!" << std::endl;
// }
if (new_enum::value3 == new_enum::value4) {
std::cout << "new_enum::value3 == new_enum::value4" << std::endl;
}
std::cout << new_enum::value3 << std::endl;
return 0;
}
