use of enum E without previous declaration 因为C++98标准中没有支持枚举类型前向声明,所以就不能保证上面的写法对任何编译器都行。为什么枚举类型不能被前向声明呢? 因为编译器无法知道枚举变量所需的存储空间。 在编译期,C ++编译器要为变量保留存储空间。 如果所有可见的都是前向声明,那么编译器无法知道选择哪...
使用-features=extensions时,编译器允许对enum类型和变量进行前向声明。此外,编译器允许声明不完整enum类型的变量。编译器总是假定不完整enum类型的大小和范围与当前平台上的int类型相同。 以下是两行无效代码示例,如果使用-features=extensions选项,可对其进行编译。 enum E; // invalid: forward declaration of enum n...
Besides that it is not needed, it is not proper C, and Clang warns that "forward references to 'enum' types are a Microsoft extension" (-Wmicrosoft-enum-forward-reference). Frankly, I have no idea what that forward declaration is supposed to do, and that this apparently hasn't come up...
// forward declaration enum class Status; // use of fwd-declared enum void continueProcessing(Status s); 2) 潜在类型 enum class 的潜在类型 (underlying type),缺省为 int 型,当然也可自定义潜在类型。无论哪种方式,编译器都会预先知道枚举成员的大小 // underlying type is int enum class Status; ...
On 64-bit architectures, it is possible for anenumto require a size that is larger than typeint. If that is the case, and if the forward declaration and the definition are visible in the same compilation, the compiler will emit an error. If the actual size is not the assumed size and...
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Apply enum forward declaration (ECodeType) bba5c40 sonarqubecloud bot commented Mar 19, 2025 Quality Gate passed Issues 0 New issues 0 Accepted issues Measures 0 Security Hotspots 0.0% Coverage on New Code 0.0% Duplication on New Code See analysis details on SonarQube Cloud AppVeyorBot comme...
// forward declaration enum class Status; // use of fwd-declared enum void continueProcessing(Status s); 1. 2. 3. 4. 5. 2) 潜在类型 enum class 的潜在类型 (underlying type),缺省为 int 型,当然也可自定义潜在类型。无论哪种方式,编译器都会预先知道枚举成员的大小 // underlying type is int...
沒辦法指定列舉型別底層的類型,容易造成混淆、不相容、同時也沒辦法做 forward declaration 在LearnCpp.com 的《4.5a — Enum classes》這邊有舉一個傳統 enum 的例子(這邊有稍微改一下): #include <iostream> enum EColor { RED, GREEN, BLUE }; enum EFruit { APPLE, BANANA }; int main() { EColor...
// forward declaration enum class Status; // use of fwd-declared enum void continueProcessing(Status s); 2) 潜在类型enum class 的潜在类型 (underlying type),缺省为 int 型,当然也可自定义潜在类型。无论哪种方式,编译器都会预先知道枚举成员的大小1...