C#隐式类型局部变量&隐式类型数组

【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 int
var i = ;

// s is compiled as a string
var s = "Hello";

// a is compiled as int[]
var a = new[] { , ,  };

// 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 type
var anon = new { Name = "Terry", Age =  };

// list is compiled as List<int>
var list = new List<int>();

【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[] { , , ,  }; // int[]
        var b = new[] { "hello", null, "world" }; // string[]

        // single-dimension jagged array
        var c = new[]
        {
            new[]{,,,},
            new[]{,,,}
        };

        // jagged array of strings
        var d = new[]
        {
            new[]{"Luca", "Mads", "Luke", "Dinesh"},
            new[]{"Karen", "Suma", "Frances"}
        };
    }
}

　　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" }
        }
};

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