将嵌套的for循环转换为单个LINQ语句

有人可以帮我把这个嵌套结构变成一个LINQ语句吗？

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]); } } } } 

Answer 1

嵌套循环通常以多个“from”子句结束（由编译器转换为对SelectMany的调用）：

 var remoteAccessLogs = from log in EventLogs.GetEventLogs() where log.LogDisplayName == "AAA" from entry in log.Entries where entry.Source == "BBB" select entry; 

（假设在此调用之前remoteAccessLogs为空，并且您很乐意直接迭代它 – 如果需要List可以调用ToList() 。）

这是点符号forms：

 var remoteAccessLogs = EventLogs.GetEventLogs() .Where(log => log.LogDisplayName == "AAA") .SelectMany(log => log.Entries) .Where(entry => entry.Source == "BBB"); 

或者列表：

 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，因为我发现它比调用Equals方法更容易阅读。 要么会工作。

Answer 2

试试这个：

  EventLog[] logs = EventLog.GetEventLogs(); remoteAccessLogs.AddRange( logs.Where(l => l.LogDisplayName.Equals("AAA")) .Select(l => l.Entries) .Where(le => le.Source.Equals("BBB")); 

但是，如果性能是一个问题，我预计这至少会有相同的算法复杂性，如果不是更糟，因为我们再次迭代列表到AddRange。

Answer 3

请尝试以下方法：

 from log in logs where log.LogDisplayName.Equals("AAA") select (from entry in log.Entries where entry.Source.Equals("BBB") select entry); 

Answer 4

我有这个解决方案，我假设remoteAccessLogs是List类型

 remoteAccessLogs.AddRange( from log in EventLog.GetEventLogs() from entry in log.Entries.Cast() select entry ); 

编辑

我忘记了where子句

 List remoteAccessLogs = new List(); remoteAccessLogs.AddRange( from log in EventLog.GetEventLogs() where log.LogDisplayName.Equals("AAA") from entry in log.Entries.Cast() where entry.Source.Equals("BBB") select entry ); 

Answer 5

看一看：

 List result = new List(); GetEventLogs().Where(x => x.LogDisplayName.Equals("AAA")).ToList().ForEach(delegate(Log en) { en.Entries.Where(y => y.Source.Equals("BBB", StringComparison.InvariantCultureIgnoreCase)).ToList().ForEach(delegate(Entries ent) { result.Add(ent); }); });