Lambda 表达式中的变量范围

delegate bool D();
delegate bool D2(int i);

class Test
{
    D del;
    D2 del2;
    public void TestMethod(int input)
    {
        int j = 0;
        // Initialize the delegates with lambda expressions.
        // Note access to 2 outer variables.
        // del will be invoked within this method.
        del = () => { j = 10;  return j > input; };

        // del2 will be invoked after TestMethod goes out of scope.
        del2 = (x) => {return x == j; };

        // Demonstrate value of j:
        // Output: j = 0 
        // The delegate has not been invoked yet.
        Console.WriteLine("j = {0}", j);        // Invoke the delegate.
        bool boolResult = del();

        // Output: j = 10 b = True
        Console.WriteLine("j = {0}. b = {1}", j, boolResult);
    }

    static void Main()
    {
        Test test = new Test();
        test.TestMethod(5);

        // Prove that del2 still has a copy of
        // local variable j from TestMethod.
        bool result = test.del2(10);

        // Output: True
        Console.WriteLine(result);

        Console.ReadKey();
    }
}

Lambda 表达式中的变量范围

posted on 2016-11-14 11:46  算顺网  阅读(748)  评论(0编辑  收藏  举报

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