强烈的范围

最新推荐文章于 2024-09-10 16:27:23 发布

原创最新推荐文章于 2024-09-10 16:27:23 发布 · 280 阅读

0 ·

CC 4.0 BY-SA版权

本文探讨了C++11引入的枚举类特性，解释了传统枚举与枚举类的区别，特别是在类型安全性和防止不当比较方面的作用。通过示例展示了如何使用枚举类，并强调了其在提高代码质量和维护性方面的优势。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
#include <iostream>
using namespace std;
 
int main()
{
    enum Color
    {
        RED,
        BLUE
    };
 
    enum Fruit
    {
        BANANA,
        APPLE
    };
 
    Color a = RED;
    Fruit b = BANANA;
 
    if (a == b) // The compiler will compare a and b as integers
        cout << "a and b are equal" << endl; // and find they are equal!
    else
        cout << "a and b are not equal" << endl;
 
    return 0;
}

当C + +比较A和B，这是比较他们为整数，这意味着在上面的例子中，一个确实等于B因为他们都默认为整数0。这是绝对没有希望从A和B是从不同的枚举！

C + + 11定义了一个新的概念，枚举类，使两个强类型的枚举和强烈的范围。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
int main()
{
    enum class Color
    {
        RED,
        BLUE
    };
 
    enum class Fruit
    {
        BANANA,
        APPLE
    };
 
    Color a = Color::RED; // note: RED is not accessible any more, we have to use Color::RED
    Fruit b = Fruit::BANANA; // note: BANANA is not accessible any more, we have to use Fruit::BANANA
 
    if (a == b) // compile error here, as the compiler doesn't know how to compare different types Color and Fruit
        cout << "a and b are equal" << endl;
    else
        cout << "a and b are not equal" << endl;
 
    return 0;
}