问题描述
考虑这样一种情况，您要检索 中所有选定复选框的值的 List 或 IEnumerable代码>.
Consider a scenario where you want to retrieve a List or IEnumerable of the values of all the selected checkboxes in an <asp:CheckBoxList>.
这是当前的实现:
IEnumerable<int> allChecked = (from item in chkBoxList.Items.Cast<ListItem>()
where item.Selected
select int.Parse(item.Value));
问题:您将如何使用 lambda 表达式或 lambda 语法改进此 LINQ 查询?
Question: How would you improve this LINQ query using a lambda expression or lambda syntax?
推荐答案
您在使用 lambda 表达式 - 它们只是被您使用 C# 的查询运算符所隐藏.
You are using lambda expressions - they are just concealed by your use of C#'s query operators.
考虑一下:
IEnumerable<int> allChecked = (from item in chkBoxList.Items.Cast<ListItem>()
where item.Selected
select int.Parse(item.Value));
编译成这样:
IEnumerable<int> allChecked = chkBoxList.Items.Cast<ListItem>()
.Where(i => i.Selected)
.Select(i => int.Parse(i.Value));
如您所见，您已经在使用两个 lambda 表达式(它们是 Where 和 Select 方法的参数)，而您甚至都不知道！这个查询很好，我根本不会改变它.
As you can see you are already using two lambda expressions (they are the parameters to the Where and Select methods) and you didn't even know it! This query is fine and I wouldn't change it at all.
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