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C#隐式类型局部变量&隐式类型数组

2024-07-12 11:13:41   222人阅读

【隐式类型局部变量】

　　可以赋予局部变量推断“类型”var 而不是显式类型。var 关键字指示编译器根据初始化语句右侧的表达式推断变量的类型。推断类型可以是内置类型、匿名类型、用户定义类型或 .NET Framework 类库中定义的类型。　　

// i is compiled as an intvar i = 5;// s is compiled as a stringvar s = "Hello";// a is compiled as int[]var a = new[] { 0, 1, 2 };// expr is compiled as IEnumerable<Customer>// or perhaps IQueryable<Customer>var expr =    from c in customers    where c.City == "London"    select c;// anon is compiled as an anonymous typevar anon = new { Name = "Terry", Age = 34 };// list is compiled as List<int>                             var list = new List<int>();
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【隐式类型数组】

　　可以创建隐式类型的数组，在这样的数组中，数组实例的类型是从数组初始值设定项中指定的元素推断而来的。

class ImplicitlyTypedArraySample{    static void Main()    {        var a = new[] { 1, 10, 100, 1000 }; // int[]        var b = new[] { "hello", null, "world" }; // string[]        // single-dimension jagged array        var c = new[]           {              new[]{1,2,3,4},            new[]{5,6,7,8}        };        // jagged array of strings        var d = new[]           {            new[]{"Luca", "Mads", "Luke", "Dinesh"},            new[]{"Karen", "Suma", "Frances"}        };    }}
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　　可以和隐匿类型一起使用。

var contacts = new[] {    new {            Name = " Eugene Zabokritski",            PhoneNumbers = new[] { "206-555-0108", "425-555-0001" }        },    new {            Name = " Hanying Feng",            PhoneNumbers = new[] { "650-555-0199" }        }};
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参考：

1、http://msdn.microsoft.com/zh-cn/library/bb383973(v=vs.90).aspx

2、http://msdn.microsoft.com/zh-cn/library/bb384061(v=vs.90).aspx

3、http://msdn.microsoft.com/zh-cn/library/bb384090(v=vs.90).aspx


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