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使用LINQ在C ++ / CLI。我发现一个专注于VS 2008的帖子，需要一系列的System :: String类的解决方法。我看到一些框架替换CodeProject，但我想知道是否有一种方法直接在C + + / CLI中使用它。如果可以，任何人都有一个很好的例子。

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，但你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 中的各个类上定义的常规方法，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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