是否可以写出类似于下面的内容?

public const string[] Titles = { "German", "Spanish", "Corrects", "Wrongs" };

当前回答

为了我的需要,我定义了静态数组,而不是不可能的const,它工作: 公共静态字符串[]title ={"德语","西班牙语","纠正","错误"};

其他回答

从c# 6开始,你可以这样写:

public static string[] Titles => new string[] { "German", "Spanish", "Corrects", "Wrongs" };

参见:c#:新的和改进的c# 6.0(特别是“表达式体函数和属性”一章)

这将使一个只读的静态属性,但它仍然允许您更改返回的数组的内容,但当您再次调用该属性时,您将再次获得原始的、未更改的数组。

为了澄清,这段代码与(或实际上是缩写)相同:

public static string[] Titles
{
    get { return new string[] { "German", "Spanish", "Corrects", "Wrongs" }; }
}

请注意,这种方法有一个缺点:每个引用实际上都会实例化一个新数组,因此如果您使用的是一个非常大的数组,这可能不是最有效的解决方案。 但是如果你重复使用相同的数组(例如把它放在一个私有属性中),它将再次打开改变数组内容的可能性。

如果你想要一个不可变数组(或列表),你也可以使用:

public static IReadOnlyList<string> Titles { get; } = new string[] { "German", "Spanish", "Corrects", "Wrongs" };

但是,这仍然有更改的风险,因为你仍然可以将其转换回字符串[]并更改内容,如下所示:

((string[]) Titles)[1] = "French";

你不能创建一个“const”数组,因为数组是对象,只能是对象 在运行时创建,const实体在编译时解析。

你可以将数组声明为“readonly”。这是 与const的效果相同,只是该值可以在运行时设置。它只能是 设置一次,之后它就是一个只读(即const)值。

数组可能是一种只能在这里求值的东西 运行时。常量必须在编译时求值。尝试使用"readonly" 而不是"const"。

.NET Framework v4.5+解决方案,改进了tdbeckett的答案:

using System.Collections.ObjectModel;

// ...

public ReadOnlyCollection<string> Titles { get; } = new ReadOnlyCollection<string>(
  new string[] { "German", "Spanish", "Corrects", "Wrongs" }
);

注意:假定集合在概念上是常量,在类级别声明它时将其设置为静态可能是有意义的。

上面的:

Initializes the property's implicit backing field once with the array. Note that { get; } - i.e., declaring only a property getter - is what makes the property itself implicitly read-only (trying to combine readonly with { get; } is actually a syntax error). Alternatively, you could just omit the { get; } and add readonly to create a field instead of a property, as in the question, but exposing public data members as properties rather than fields is a good habit to form. Creates an array-like structure (allowing indexed access) that is truly and robustly read-only (conceptually constant, once created), both with respect to: preventing modification of the collection as a whole (such as by removing or adding elements, or by assigning a new collection to the variable). preventing modification of individual elements. (Even indirect modification isn't possible - unlike with an IReadOnlyList<T> solution, where a (string[]) cast can be used to gain write access to the elements, as shown in mjepsen's helpful answer. The same vulnerability applies to the IReadOnlyCollection<T> interface, which, despite the similarity in name to class ReadOnlyCollection, does not even support indexed access, making it fundamentally unsuitable for providing array-like access.)

可以将数组声明为只读数组,但请记住,可以更改只读数组的元素。

public readonly string[] Titles = { "German", "Spanish", "Corrects", "Wrongs" };
...
Titles[0] = "bla";

可以考虑像Cody建议的那样使用enum或IList。

public readonly IList<string> ITitles = new List<string> {"German", "Spanish", "Corrects", "Wrongs" }.AsReadOnly();