本文主要向大家介绍了C#编程优化基础学习之枚举，通过具体的内容向大家展示，希望对大家学习C#编程有所帮助。

1. 枚举： 

public enum Planet {

    MERCURY,

    VENUS,

    EARTH,

    MARS,

    JUPITER,

    SATURN,

    URANUS,

    NEPTUNE,

    PLUTO // Pluto is a planet!!!

}

2.对应的质量 

public float GetMass(Planet planet) {

    switch(planet) {

        case Planet.MERCURY:

            return 0.330;

        case Planet.VENUS:

            return 4.87f;

        case Planet.EARTH:

            return 5.97f;

        ...

        case Planet.PLUTO:

            return 0.0146f;

    }

}

3。要是多个属性就不方便:

行星直径又如何？ 另一个switch语句？ 密度怎么样？ 重力？ 逃跑速度？ 只要想想你将要维护的switch语句的数量。 你可以争辩说，你可以使用一个Dictionary，但仍然笨重。 每个数据的Dictionary都要映射？没门。

有一个更好的方法，我会告诉你如何。 这可能已经是非Unity程序员的常识，但我想在我的博客中再次提出这个冗余的主题，对于那些可能不知道这一点的人来说，特别是初学者。 我也想保持简单。

基本上，你可以使用类作为枚举。 为什么用类？ 这确实表现的更好 您可以存储任意数量的任意数据。 您甚至可以存储例程或功能。 你可以做很多事情。 唯一的要求是它是不可变的，这意味着类一个实例的状态在整个程序期间都不能改变。以下是Planet枚举用类表示的一个版本：  

public class Planet {

       // The different values

       public static readonly Planet MERCURY = new Planet(0, 0.330f, 4879, 5427, 3.7f);

       public static readonly Planet VENUS = new Planet(1, 4.87f, 12104, 5243, 8.9f);

       public static readonly Planet EARTH = new Planet(2, 5.97f, 12756, 5514, 9.8f);

       public static readonly Planet MARS = new Planet(3, 0.642f, 6792, 3933, 3.7f);

       public static readonly Planet JUPITER = new Planet(4, 1898.0f, 142984, 1326, 23.1f);

       public static readonly Planet SATURN = new Planet(5, 568.0f, 120536, 687, 9.0f);

       public static readonly Planet URANUS = new Planet(6, 86.8f, 51118, 1271, 8.7f);

       public static readonly Planet NEPTUNE = new Planet(7, 102.0f, 49528, 1638, 11.0f);

       public static readonly Planet PLUTO = new Planet(8, 0.0146f, 2370, 2095, 0.7f);

       // Use readonly to maintain immutability

       private readonly int id;

       private readonly float mass; // in 10^24 kg

       private readonly int diameter; // in km

       private readonly int density; // in kg/m^3

       private readonly float gravity; // in m/s^2

       // We use a private constructor because this should not be instantiated

       // anywhere else.

       private Planet(int id, float mass, int diameter, int density, float gravity) {

           this.id = id;

           this.mass = mass;

           this.diameter = diameter;

           this.density = density;

           this.gravity = gravity;

       }

       public int Id {

           get {

               return id;

           }

       }

       public float Mass {

           get {

               return mass;

           }

       }

       public int Diameter {

           get {

               return diameter;

           }

       }

       public int Density {

           get {

               return density;

           }

       }

       public float Gravity {

           get {

               return gravity;

           }

       }

   }

使用:

ship.TargetPlanet = Planet.NEPTUNE;

// Want to know the target planet's mass

float mass = ship.TargetPlanet.Mass;

// Density

int density = ship.TargetPlanet.Density;

5.我们已经消除了切换语句或字典来维护不同行星信息的需要。 想要一个新的行星状态？ 只需添加一个新的成员变量并在实例化上指定它们。

如何从其他数据类型转换？ 喜欢说从int id转换为Planet实例？ 这很容易 通常我为这些转换添加了一个公共和静态方法。 例如：  

public class Planet {

    // The different values

    public static readonly Planet MERCURY = new Planet(0, 0.330f, 4879, 5427, 3.7f);

    public static readonly Planet VENUS = new Planet(1, 4.87f, 12104, 5243, 8.9f);

    public static readonly Planet EARTH = new Planet(2, 5.97f, 12756, 5514, 9.8f);

    public static readonly Planet MARS = new Planet(3, 0.642f, 6792, 3933, 3.7f);

    public static readonly Planet JUPITER = new Planet(4, 1898.0f, 142984, 1326, 23.1f);

    public static readonly Planet SATURN = new Planet(5, 568.0f, 120536, 687, 9.0f);

    public static readonly Planet URANUS = new Planet(6, 86.8f, 51118, 1271, 8.7f);

    public static readonly Planet NEPTUNE = new Planet(7, 102.0f, 49528, 1638, 11.0f);

    public static readonly Planet PLUTO = new Planet(8, 0.0146f, 2370, 2095, 0.7f);

    // This can be used to loop through all planets

    public static Planet[] ALL = new Planet[] {

        MERCURY, VENUS, EARTH, MARS, JUPITER, SATURN, URANUS, NEPTUNE, PLUTO

    };

    // Converts the specified id to a Planet instance

    public static Planet Convert(int id) {

        for(int i = 0; i < ALL.Length; ++i) {

            if(ALL.Id == id) {

                return ALL;

            }

        }

        // return ALL[id] could also work here but what if a non sequential id is used

        throw new Exception("Cannot convert {0} to a Planet.".FormatWith(id));

    }

    ...

}

// Usage

Planet planet = Planet.Convert(someIntPlanet);

也可以用继承

private static Dictionary<string, planet=""> ALL = new Dictionary<string, planet="">() {

    { MERCURY.TextId, MERCURY },

    { VENUS.TextId, VENUS },

    { EARTH.TextId, EARTH },

    ...

    { PLUTO.TextId, PLUTO },

};

// Converts the specified string to a Planet instance

public static Planet Convert(string id) {

    return ALL[id];

}</string,></string,>

您现在可以添加功能。 你可以这样做：

Planet currentPlanet = Planet.VENUS;

currentPlanet.ApplyGravity(ship);

The coolest thing for me is you can specify different actions or behavior to the enum values. Something like this (It’s very contrived but you get the idea.):

public static readonly Planet EARTH = new Planet(2, 5.97f, 12756, 5514, 9.8f, delegate(Ship ship) {

    // Actions on land of ship

    ship.AddFood(1000);

    ship.RetireCrew();

    ship.RecruitNewCrew();

});

public static readonly Planet MARS = new Planet(3, 0.642f, 6792, 3933, 3.7f, delegate(Ship ship) {

    // Actions on land of ship

    ship.DeductFood(50);

    ship.Research();

    ship.Mine();

});

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