我有一个包含int类型的数组的List。 使用lambda表达式如何选择索引大于2的所有项目的列表？
例如，下面的列表应返回8和9：
var items = new List<object>() { new int[3] { 1, 2, 3 }, new int[1] { 4 }, new int[5] { 5, 6, 7, 8, 9 } }; //var overTwoIndexItems = ?I have a List which contains arrays of type int. Using a lambda expression how can I select a list of all items with an index bigger than 2?
For example the list below should return 8 and 9:
var items = new List<object>() { new int[3] { 1, 2, 3 }, new int[1] { 4 }, new int[5] { 5, 6, 7, 8, 9 } }; //var overTwoIndexItems = ?最满意答案
您可以使用Skip跳过每个数组中的前三项（即索引为0,1和2的项）。 您可以使用SelectMany来平展结果：
var overTwoIndexItems = items.SelectMany(a => ((int[])a).Skip(3));或者更安全的版本（当你向对象列表中添加非整数数组的东西时会处理这种情况）：
var overTwoIndexItems = items.OfType<int[]>().SelectMany(a => a.Skip(3));结果：
8, 9顺便说一句：你为什么使用object列表？ 这看起来像ArrayList 。 泛型的要点是强类型参数。 请改用List<int[]> 。 然后查询将如下所示：
items.SelectMany(a => a.Skip(3))You can use Skip to skip first three items in each array (i.e. items with indexes 0, 1 and 2). And you can use SelectMany to flatten results:
var overTwoIndexItems = items.SelectMany(a => ((int[])a).Skip(3));Or more safe version (which will handle case when you are adding something that is not integer array to your list of objects):
var overTwoIndexItems = items.OfType<int[]>().SelectMany(a => a.Skip(3));Result:
8, 9BTW: Why are you using list of object? That looks like ArrayList. Main point of generics is strongly-typed arguments. Use List<int[]> instead. Then query will look like:
items.SelectMany(a => a.Skip(3))Lambda表达式选择index> x的所有项目(Lambda expression to select all items where index > x)我有一个包含int类型的数组的List。 使用lambda表达式如何选择索引大于2的所有项目的列表？
例如，下面的列表应返回8和9：
var items = new List<object>() { new int[3] { 1, 2, 3 }, new int[1] { 4 }, new int[5] { 5, 6, 7, 8, 9 } }; //var overTwoIndexItems = ?I have a List which contains arrays of type int. Using a lambda expression how can I select a list of all items with an index bigger than 2?
For example the list below should return 8 and 9:
var items = new List<object>() { new int[3] { 1, 2, 3 }, new int[1] { 4 }, new int[5] { 5, 6, 7, 8, 9 } }; //var overTwoIndexItems = ?最满意答案
您可以使用Skip跳过每个数组中的前三项（即索引为0,1和2的项）。 您可以使用SelectMany来平展结果：
var overTwoIndexItems = items.SelectMany(a => ((int[])a).Skip(3));或者更安全的版本（当你向对象列表中添加非整数数组的东西时会处理这种情况）：
var overTwoIndexItems = items.OfType<int[]>().SelectMany(a => a.Skip(3));结果：
8, 9顺便说一句：你为什么使用object列表？ 这看起来像ArrayList 。 泛型的要点是强类型参数。 请改用List<int[]> 。 然后查询将如下所示：
items.SelectMany(a => a.Skip(3))You can use Skip to skip first three items in each array (i.e. items with indexes 0, 1 and 2). And you can use SelectMany to flatten results:
var overTwoIndexItems = items.SelectMany(a => ((int[])a).Skip(3));Or more safe version (which will handle case when you are adding something that is not integer array to your list of objects):
var overTwoIndexItems = items.OfType<int[]>().SelectMany(a => a.Skip(3));Result:
8, 9BTW: Why are you using list of object? That looks like ArrayList. Main point of generics is strongly-typed arguments. Use List<int[]> instead. Then query will look like:
items.SelectMany(a => a.Skip(3))
发布评论