如何在 C++/CLI 中使用 LINQ - 在 VS 2010/.Net 4.0 中 [英] How to use LINQ in C++/CLI - in VS 2010/.Net 4.0
问题描述
只是想知道是否有一种方法可以在 C++/CLI 中使用 LINQ.我找到了一篇专注于 VS 2008 的帖子,并且需要为 System::String 类提供一系列解决方法.我在 CodeProject 上看到了一些框架替换,但我想知道是否有一种方法可以直接在 C++/CLI 中使用它.如果可以,谁有好的例子?
Just wondering if there is a way to use LINQ in C++/CLI. I found one post that was focused on VS 2008 and required a bunch of workarounds for the System::String class. I have seen some framework replacements on CodeProject, but I was wondering if there is a way to use it directly in C++/CLI. If you can, anyone have a good example?
推荐答案
您可以使用在 System::Linq
命名空间中定义的 Linq 方法,但您必须跳过几个额外的箍.
You can use the Linq methods that are defined in the System::Linq
namespace, but you'll have to jump through a couple extra hoops.
首先,C++/CLI 不支持扩展方法.但是,扩展方法是在System::Linq
中定义在各个类上的常规方法,因此您可以直接调用它们.
First, C++/CLI doesn't support extension methods. However, the extension methods are regular methods defined on various classes in System::Linq
, so you can call them directly.
List<int>^ list = gcnew List<int>();
int i = Enumerable::FirstOrDefault(list);
其次,C++/CLI 不支持 lambda 表达式.唯一的解决方法是声明一个实际的方法,并将其作为委托传递.
Second, C++/CLI doesn't support lambda expressions. The only workaround is to declare an actual method, and pass that as a delegate.
ref class Foo
{
public:
static bool GreaterThanZero(int i) { return i > 0; }
void Bar()
{
List<int>^ list = gcnew List<int>();
int i = Enumerable::FirstOrDefault(list, gcnew Func<int, bool>(&Foo::GreaterThanZero));
}
}
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