获取所有匹配项的索引 [英] Getting indexes of all matching items
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问题描述
我想获取枚举中与给定条件匹配的所有项目的索引.有没有比这更清洁的方法了?
I want to get the index of all items in an enumerable that match a given condition. Is there a cleaner way than this?
var indexes = list.Select((item, index) => new { Item = item, Index = index }).Where(o => Condition(o.Item)).Select(o => o.Index);
推荐答案
使用标准LINQ to Object方法-不,没有.您只能通过将查询分成几行来提高可读性:
Using standard LINQ to Object methods - no, there's not. You only can improve readability by splitting your query into couple lines:
var indexes = list.Select((item, index) => new { Item = item, Index = index })
.Where(o => Condition(o.Item))
.Select(o => o.Index);
但是,您可以为此编写扩展方法:
However, you can write an Extension Method for that:
public static IEnumerable<int> IndexesWhere<T>(this IEnumerable<T> source, Func<T, bool> predicate)
{
int index=0;
foreach (T element in source)
{
if (predicate(element))
{
yield return index;
}
index++;
}
}
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