C++核心準(zhǔn)則Enum.7: 只在必要時(shí)定義枚舉的底層類型

Enum.7: Specify the underlying type of an enumeration only when necessary

Enum.7:? 只在必要時(shí)定義枚舉的底層類型

Reason(原因)

The default is the easiest to read and write.?int?is the default integer type.?int?is compatible with C?enums.

默認(rèn)的類型更容易讀寫。int是默認(rèn)的整數(shù)類型。int和C語言枚舉類型兼容。

Example(示例)

enum class Direction : char { n, s, e, w,
                              ne, nw, se, sw };  // underlying type saves space

enum class Web_color : int32_t { red   = 0xFF0000,
                                 green = 0x00FF00,
                                 blue  = 0x0000FF };  // underlying type is redundant

Note(注意)

Specifying the underlying type is necessary in forward declarations of enumerations:

在前置聲明枚舉時(shí)需要定義枚舉的底層類型。

enum Flags : char;

void f(Flags);

// ....

enum flags : char { /* ... */ };

Enforcement(實(shí)施建議)

????

原文鏈接：

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#enum7-specify-the-underlying-type-of-an-enumeration-only-when-necessary

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