问题: 尽管enum class增强了类型安全,但直接的整数赋值或比较仍可能编译通过。 代码语言:cpp 代码运行次数:0 运行 AI代码解释 Color color = static_cast<Color>(2); // 非枚举值赋给枚举变量 if (color == 2) { // 应避免这样的比较 } 解决方案: 避免非枚举值的直接赋值或比较,使用显式
enum class UserInfoFields { uiName, uiEmail, uiReputation }; UserInfo uInfo; // as before … auto val = std::get<static_cast<std::size_t>(UserInfoFields::uiEmail)>(uInfo); 此时,可用模板函数,将枚举成员 UserInfoFields::uiEmail 和 std::size_t 类型联系起来 template<typename E> const...
getDeclaringClass()) throw new ClassCastException(); return self.ordinal - other.ordinal; } public final Class<E> getDeclaringClass() { Class<?> clazz = getClass(); Class<?> zuper = clazz.getSuperclass(); return (zuper == Enum.class) ? (Class<E>)clazz : (Class<E>)zuper; } public...
{ auto factors = primeFactors(static_cast<std::size_t>(c)); // suspect, but it compiles ... ... } 1.3 前置声明enum class 支持前置声明,即不用初始化枚举成员,声明一个枚举类型1 enum class Color; 1) 新增枚举成员enum 在声明时,编译器会选择占用内存最小的一种潜在类型 (underlying types)...
enum class UserInfoFields { uiName, uiEmail, uiReputation }; UserInfo uInfo; // as before … auto val = std::get<static_cast<std::size_t>(UserInfoFields::uiEmail)>(uInfo); 1. 2. 3. 4. 5. 此时,可用模板函数,将枚举成员 UserInfoFields::uiEmail 和 std::size_t 类型联系起来 templat...
cast<decltype(val_)>(v)}{}constexpr两者合并_且统一类型(enum添加的v)noexcept:val_{static_cast<...
{returnos <<static_cast<char>(al); }inttest_enum_class_1(){ color col = red; altitude a; a = altitude::low; std::cout <<"col = "<< col <<'\n'<<"a = "<< a <<'\n'<<"f = "<< f <<'\n';return0; }/// reference: https://stackoverflow.com/questions/18335861/why...
(2)compareTo()方法: Enum实现了java.lang Comparable接口,因此可以比较象与指定对象的顺序。Enum中的compareTo返回的是两个枚举值的顺序之差。当然,前提是两个枚举值必须属于同一个枚举类,否则会抛出ClassCastException()异常。(具体可见源代码) Color.RED.compareTo(Color.BLUE); //返回结果 -1 ...
The reason is that you can cast a numeric value to the enumeration type even if that numeric value is not defined in the enumeration. Examples The following example uses an enumeration to represent named values and another enumeration to represent named bit fields. C# 复制 using System; ...
Class ClassCastException ClassCircularityError ClassFormatError ClassLoader ClassNotFoundException ClassValue CloneNotSupportedException Compiler Deprecated DeprecatedAttribute Double Enum Enum 构造函数 属性 方法 EnumConstantNotPresentException Error Exception ExceptionInInitializerError Float FunctionalInterfaceAttribute I...