C# 用 linq 替换 foreach 循环
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Replace foreach loop with linq
提问by TOP KEK
I tried to replace code
我试图替换代码
foreach (var discovery in mpwrapper.parser.Discoveries)
{
solution.AddFile("Discoveries", discovery.DisplayStringName + ".mpx", discovery);
}
with the following linq expression
使用以下 linq 表达式
mpwrapper.parser.Discoveries.Select(
s => solution.AddFile("Discoveries", s.DisplayStringName + ".mpx", s));
But got an error
但是出错了
The type arguments for method 'System.Linq.Enumerable.Select(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
无法从用法推断方法“System.Linq.Enumerable.Select(System.Collections.Generic.IEnumerable, System.Func)”的类型参数。尝试明确指定类型参数。
How to convert this foreach loop to linq query where I execute a method on each object in my IEnumerable collection?
如何将此 foreach 循环转换为 linq 查询，在其中我对 IEnumerable 集合中的每个对象执行一个方法？
采纳答案by dotixx
I think what you need is the ForEach method ;)
我认为您需要的是 ForEach 方法；)
mpwrapper.parser.Discoveries.ToList().ForEach(s => { solution.AddFile("Discoveries", s.DisplayStringName + ".mpx", s); });
回答by user2509738
The problem is Select needs to return a value, but also Linq is not designed to mutate collections. Think of select as a transformation over the collection rather than a state change for each item
问题是 Select 需要返回一个值，而且 Linq 也不是为了改变集合而设计的。将选择视为对集合的转换，而不是每个项目的状态更改
Maybe a foreach loop is the best solution here
也许 foreach 循环是这里最好的解决方案
回答by Marko Juvan?i?
If Discoveries is a list, then do it like this
如果 Discoveries 是一个列表，那么就这样做
mpwrapper.parser.Discoveries.ForEach(discovery => solution.AddFile("Discoveries", discovery .DisplayStringName + ".mpx", discovery);
If not, convert it to List first :)
如果没有，请先将其转换为 List :)
回答by sthiers
The List<T>.ForEachmethod does the trick.
该List<T>.ForEach方法可以解决问题。
However, this method does not exist on IEnumerable<T>.
但是，该方法在 上不存在IEnumerable<T>。
回答by Alex Filipovici
Try this:
尝试这个：
mpwrapper.parser.Discoveries.ToList()
.ForEach(s =>
solution.AddFile("Discoveries", s.DisplayStringName + ".mpx", s));
回答by NPSF3000
LINQ stands for Language INtegrated Query... yet you aren't actually queryinganything.
LINQ 代表 Language INtegrated Query...但您实际上并没有查询任何内容。
If mpwrapper.parser.Discoveriesis a List<T>, you can use the ForEachmethod; or, if it is an IEnumerable, you could always add a ForEachextension method… but this is more a minor aesthetic change and has nothing to do with LINQ.
如果mpwrapper.parser.Discoveries是 a List<T>，则可以使用该ForEach方法；或者，如果它是IEnumerable，你总是可以添加一个ForEach扩展方法……但这更像是一个微小的美学变化，与 LINQ 无关。
回答by Leon van Wyk
I use a little cheat with the .All method. It simply requires a return boolean value and presents very neatly. I included a sample with embeded linq inside the .All
我在 .All 方法中使用了一个小技巧。它只需要一个返回布尔值并且非常整洁地呈现。我在 .All 文件中包含了一个带有嵌入式 linq 的示例
configurations.All(c =>
{
var gcx = globalConfigurations.FirstOrDefault(gc =>
gc.Type == c.Type && configurationGuids.Any(cGuid => gc.Guid == cGuid)
);
return true;
});
