如何将索引字段添加到Linq结果

不要使用查询表达式。使用 the overload of Select which passes you an index

var list = FileList.Select((file, index) => new { Index=index, Filename=file });

string[] values = { "a", "b", "c" };
int i = 0;
var t = (from v in values
select new { Index = i++, Value = v}).ToList();

你 无法获取索引 使用纯LINQ查询表达式(具有 from.. where.. select..

你只需要 退出LINQ查询表达式 .Select(item, index) 方法重载。

var newestExistingFilesWithIndexes = 
    (from f in Filelist
     // we love LINQ query expressions
     where f.Exists
     // and we use it anywhere possible
     orderby f.LastModified descending
     select f)
     // but sometimes we have to get out and use LINQ extension methods
    .Select((f, index) => new { Index = index, Filename = f.Fullname});

或者假设,您需要根据项目索引筛选列表。。。

var newestExistingFilesOnlyEvenIndexes = 
     // use the Select method overload to get the index
    (from f in Filelist.Select((file, index) => new { file, index })
     // only take item with an even index
     where f.index % 2 == 0
     where f.file.Exists
     orderby f.file.LastModified descending
     select f.file);