将嵌套的for循环转换为单个LINQ语句 [英] Convert nested for-loops into single LINQ statement
问题描述
有人可以帮我把这个嵌套结构变成一个LINQ语句吗?
can someone please help me turn this nested structure into a single LINQ statement?
EventLog[] logs = EventLog.GetEventLogs();
for (int i = 0; i < logs.Length; i++)
{
if (logs[i].LogDisplayName.Equals("AAA"))
{
for (int j = 0; j < logs[i].Entries.Count; j++)
{
if (logs[i].Entries[j].Source.Equals("BBB"))
{
remoteAccessLogs.Add(logs[i].Entries[j]);
}
}
}
}
推荐答案
嵌套循环通常最终会有多个from子句(由编译器转换为对 SelectMany
的调用):
Nested loops usually end up with multiple "from" clauses (which are converted into calls to SelectMany
by the compiler):
var remoteAccessLogs = from log in EventLogs.GetEventLogs()
where log.LogDisplayName == "AAA"
from entry in log.Entries
where entry.Source == "BBB"
select entry;
(假设 remoteAccessLogs
之前是空的这个电话,你很高兴直接迭代它 - 如果你想要一个 List< T> $,你可以调用
ToList()
c $ c>。)
(That's assuming that remoteAccessLogs
is empty before this call, and that you're happy iterating over it directly - you can call ToList()
if you want a List<T>
.)
以下是点符号形式:
var remoteAccessLogs = EventLogs.GetEventLogs()
.Where(log => log.LogDisplayName == "AAA")
.SelectMany(log => log.Entries)
.Where(entry => entry.Source == "BBB");
或列表:
var remoteAccessLogs = EventLogs.GetEventLogs()
.Where(log => log.LogDisplayName == "AAA")
.SelectMany(log => log.Entries)
.Where(entry => entry.Source == "BBB")
.ToList();
请注意,我使用了重载的== for string,因为我觉得它比调用更容易阅读等于
方法。要么会工作。
Note that I've used the overloaded == for string as I find it easier to read than calling the Equals
method. Either will work though.
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