Question

假设：

var a = SomeCollection.OrderBy(...)
              .Select(f => new MyType
                               {
                                  counter = ? //I want counter value, so what first
                                              //object have counter=1, second counter=2 
                                              //and so on
                                  a=f.sometthing,
                                  ...
                                });

如何设置此计数器值？或者之后我是否愿意迭代a？

Answer 1

使用Select的重载，它为您提供当前元素的基于0的索引。

.Select((item, index) => new MyType
            { 
                counter = index + 1,
                a = item.Something

Answer 2

只需捕获一个变量：

int index = 1;

var a = SomeCollection.OrderBy(...)
        .Select(x => new MyType { counter = index++; });

计数器将在调用每次迭代时递增。

linq投影元素计数

2 个答案: