如果您想获取元素的索引,可以使用以下代码:
int index = list.Select((item, i) => new { Item = item, Index = i })
.First(x => x.Item == search).Index;
// or
var tagged = list.Select((item, i) => new { Item = item, Index = i });
int index = (from pair in tagged
where pair.Item == search
select pair.Index).First();
在第一遍中,你无法摆脱 lambda。
请注意,如果该项不存在,这将抛出异常。通过使用可空整数解决该问题:
var tagged = list.Select((item, i) => new { Item = item, Index = (int?)i });
int? index = (from pair in tagged
where pair.Item == search
select pair.Index).FirstOrDefault();
如果您想获取该项:
// Throws if not found
var item = list.First(item => item == search);
// or
var item = (from item in list
where item == search
select item).First();
// Null if not found
var item = list.FirstOrDefault(item => item == search);
// or
var item = (from item in list
where item == search
select item).FirstOrDefault();
如果您想计数与某个条件匹配的项目数量:
int count = list.Count(item => item == search);
// or
int count = (from item in list
where item == search
select item).Count();
如果您想获取所有符合条件的项:
var items = list.Where(item => item == search);
// or
var items = from item in list
where item == search
select item;
在这些情况下,请不要忘记检查列表中是否存在null
。
或者使用(list ?? Enumerable.Empty<string>())
代替list
。