C + + (Analysis of enum type-enum)

Enum type

An enumeration type (enumeration) is a derived data type in C + +, which is a collection of user-defined enumeration constants.

If a variable has only a few possible values, it can be defined as an enumeration (enumeration) type. The so-called "enumeration" refers to the value of the variable is enumerated, the value of the variable can only be listed in the range of values.

To create an enumeration, you need to use the keyword enum. The general form of an enumeration type is:

enum enum -name { List of names }< Span class= "PLN" > var-list Enum-name is the name of the enumeration type. Name list {List of names} is a comma-delimited 
 
 Eg1: 
 enum color { Red, Green, Blue } C;//defines an enumeration type named color, and C is an enumeration variable.  

  < Span class= "pun" >< Span class= "pun" > C = Blue;//assign a value to the enumeration variable C                   c = Blue 
 Eg2: 
                By default, the first name has a value of 0, the second name has a value of 1, the third name has a value of 2, and so on. However, you can also assign a special value to the name, just add an initial value. For example, in the following enumeration, the value of  Green    is 5. 

Enum{ red, green=5,};       

Here, the value ofBlue is 6, because by default, each name will be 1 larger than the previous name.

eg

#include <iostream>
using namespace Std;

int main ()
{
Enum School{teacher,student,headmaster} a,b,c;
A=school (0);
B=student;
C=headmaster;
cout<<a<<endl;
cout<<b<<endl;
cout<<c<<endl;
cout << "Hello World" << Endl;
return 0;
}

Why use enumerations?

Take a look at this example:

#include<iostream> using namespace std; void main() {      int per=0;      switch (per)      {      case 0:          cout<< "中国人，牛！" <<endl;          break ;      case 1:          cout<< "美帝人，黑！" <<endl;          break ;      case 2:          cout<< "英国佬，才！" <<endl;          break ;      default :          break ;      } }

 //对比

#include<iostream> using namespace std; enum Person {      Chinese,American,English }; void main() {      Person per=American;      switch (per)      {      case Chinese:          cout<< "中国人，牛！" <<endl;          break ;      case American:          cout<< "美帝人，黑！" <<endl;          break ;      case English:          cout<< "英国佬，才！" <<endl;          break ;      default :          break ;      } }

C + + (Analysis of enum type-enum)