枚举

0. 概念

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• 理解：专门用来表示 固定类型 的 取值，本质就是 整型

  格式：enum 枚举类型名称 {
              固定类型,
       };
  
  enum Season {
    kSeasonSpring,
    kSeasonSummer,
    kSeasonAutumn,
    kSeasonWinter
  };
  

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1. 定义

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• 形式

  1. 先定义枚举类型，再定义枚举变量
     enum Gender {
       kGenderMale,
       kGenderFemale
     };
     enum Gender sex;
  
  2. 定义枚举类型同时定义枚举变量
     enum Gender {
       kGenderMale,
       kGenderFemale
     } sex;
   
  3. 定义枚举类型同时定义枚举变量，省略枚举类型名称
     enum {
       kGenderMale,
       kGenderFemale
     } sex;
  

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2. 初始化

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• 形式

  1. 默认情况下, 枚举的第0个取值就是整数0, 后面取值依次递增1
     enum Gender {
       kGenderMale,
       kGenderFemale
     };
     enum Gender sex;
     sex = kGenderMale;
     printf("%i\n", sex);
     sex = kGenderFemale;
     printf("%i\n", sex);
  
  2. 可以给枚举固定类型赋值，后面取值依次递增1
     enum Season {
       kSeasonSpring = 99,
       kSeasonSummer,
       kSeasonAutumn,
       kSeasonWinter
     } es = kSeasonSpring;;
     printf("%i\n", es);
     es = kSeasonSummer;
     printf("%i\n", es);
  

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