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]);
}
}
}
}
嵌套循环通常最终会有多个“from”子句(转换为调用 SelectMany
由编译器):
var remoteAccessLogs = from log in EventLogs.GetEventLogs()
where log.LogDisplayName == "AAA"
from entry in log.Entries
where entry.Source == "BBB"
select entry;
(那就是假设 remoteAccessLogs
在此调用之前是空的,并且您很乐意直接迭代它 - 您可以调用 ToList()
如果你想要一个 List<T>
。)
这是点符号形式:
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,我已经使用了重载的== for string,因为我发现它比调用它更容易阅读 Equals
方法。要么会工作。
嵌套循环通常最终会有多个“from”子句(转换为调用 SelectMany
由编译器):
var remoteAccessLogs = from log in EventLogs.GetEventLogs()
where log.LogDisplayName == "AAA"
from entry in log.Entries
where entry.Source == "BBB"
select entry;
(那就是假设 remoteAccessLogs
在此调用之前是空的,并且您很乐意直接迭代它 - 您可以调用 ToList()
如果你想要一个 List<T>
。)
这是点符号形式:
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,我已经使用了重载的== for string,因为我发现它比调用它更容易阅读 Equals
方法。要么会工作。
尝试这个:
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。
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);
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<EventLogEntry>()
select entry
);
编辑
我忘记了where子句
List<EventLogEntry> remoteAccessLogs = new List<EventLogEntry>();
remoteAccessLogs.AddRange(
from log in EventLog.GetEventLogs()
where log.LogDisplayName.Equals("AAA")
from entry in log.Entries.Cast<EventLogEntry>()
where entry.Source.Equals("BBB")
select entry
);
看一看:
List<Entries> result = new List<Entries>();
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);
});
});