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jswxcathay596200 2002-09-10
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学习!
Chiun 2002-09-10
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enum是枚举类型，在声明该类型同时，也对其今后实例化后变量的取值范围做出了限定。
everandforever 2002-09-10
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C里面就有吧,基础要打好哟.
asan_xu 2002-09-10
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up
余山水 2002-09-10
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enum叫枚举类型
zjkzyh 2002-09-10
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enum
enum [tag] {enum-list} [declarator]; // for definition of enumerated type
enum tag declarator; // for declaration of variable of type tag
The enum keyword specifies an enumerated type.
An enumerated type is a user-defined type consisting of a set of named constants called enumerators. By default, the first enumerator has a value of 0, and each successive enumerator is one larger than the value of the previous one, unless you explicitly specify a value for a particular enumerator. Enumerators needn’t have unique values. The name of each enumerator is treated as a constant and must be unique within the scope where the enum is defined. An enumerator can be promoted to an integer value. However, converting an integer to an enumerator requires an explicit cast, and the results are not defined.
In C, you can use the enum keyword and the tag to declare variables of the enumerated type. In C++, you can use the tag alone.
In C++, enumerators defined within a class are accessible only to member functions of that class unless qualified with the class name (for example, class_name::enumerator). You can use the same syntax for explicit access to the type name (class_name::tag).
For related information, see class and struct.
Example
// Example of the enum keyword
enum Days // Declare enum type Days
{
saturday, // saturday = 0 by default
sunday = 0, // sunday = 0 as well
monday, // monday = 1
tuesday, // tuesday = 2
wednesday, // etc.
thursday,
friday
} today; // Variable today has type Days
int tuesday; // Error, redefinition of tuesday
enum Days yesterday; // Legal in C and C++
Days tomorrow; // Legal in C++ only
yesterday = monday;
int i = tuesday; // Legal; i = 2
yesterday = 0; // Error; no conversion
yesterday = (Days)0; // Legal, but results undefined
自己可已看MSDN,另外 enum叫枚举类型
enum [tag] {enum-list} [declarator]; // for definition of enumerated type
enum tag declarator; // for declaration of variable of type tag
The enum keyword specifies an enumerated type.
An enumerated type is a user-defined type consisting of a set of named constants called enumerators. By default, the first enumerator has a value of 0, and each successive enumerator is one larger than the value of the previous one, unless you explicitly specify a value for a particular enumerator. Enumerators needn’t have unique values. The name of each enumerator is treated as a constant and must be unique within the scope where the enum is defined. An enumerator can be promoted to an integer value. However, converting an integer to an enumerator requires an explicit cast, and the results are not defined.
In C, you can use the enum keyword and the tag to declare variables of the enumerated type. In C++, you can use the tag alone.
In C++, enumerators defined within a class are accessible only to member functions of that class unless qualified with the class name (for example, class_name::enumerator). You can use the same syntax for explicit access to the type name (class_name::tag).
For related information, see class and struct.
Example
// Example of the enum keyword
enum Days // Declare enum type Days
{
saturday, // saturday = 0 by default
sunday = 0, // sunday = 0 as well
monday, // monday = 1
tuesday, // tuesday = 2
wednesday, // etc.
thursday,
friday
} today; // Variable today has type Days
int tuesday; // Error, redefinition of tuesday
enum Days yesterday; // Legal in C and C++
Days tomorrow; // Legal in C++ only
yesterday = monday;
int i = tuesday; // Legal; i = 2
yesterday = 0; // Error; no conversion
yesterday = (Days)0; // Legal, but results undefined
自己可已看MSDN,另外 enum叫枚举类型
