C# into子句

时间:2021-03-23 23:27:04

可使用 into 上下文关键字创建临时标识符,将 groupjoin 或 select 子句的结果存储至新标识符。 此标识符本身可以是附加查询命令的生成器。 有时称在 group 或 select 子句中使用新标识符为“延续”。

示例

下面的示例演示使用 into 关键字来启用具有推断类型 IGrouping 的临时标识符 fruitGroup。 通过使用该标识符,可对每个组调用 Count 方法,并且仅选择那些包含两个或更多个单词的组。

class IntoSample1
{
static void Main()
{ // Create a data source.
string[] words = { "apples", "blueberries", "oranges", "bananas", "apricots"}; // Create the query.
var wordGroups1 =
from w in words
group w by w[] into fruitGroup
where fruitGroup.Count() >=
select new { FirstLetter = fruitGroup.Key, Words = fruitGroup.Count() }; // Execute the query. Note that we only iterate over the groups,
// not the items in each group
foreach (var item in wordGroups1)
{
Console.WriteLine(" {0} has {1} elements.", item.FirstLetter, item.Words);
} // Keep the console window open in debug mode
Console.WriteLine("Press any key to exit.");
Console.ReadKey();
}
}
/* Output:
a has 2 elements.
b has 2 elements.
*/