LINQ 用法，返回结果不是在定义时取值，而是在调用时实时取值，有意思！

最新推荐文章于 2024-01-19 12:21:23 发布

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最新推荐文章于 2024-01-19 12:21:23 发布

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原文链接：http://www.cnblogs.com/weiweiboqi/p/6210432.html

本文通过一个C#中的LINQ查询示例展示了如何筛选并打印以J开头的名字，并讨论了延迟加载与立即加载的区别。

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var names = new List<string> { "Nino o", "Alberto", "Juan", "Mike", "phi1" };
            var namesWithJ = from n in names
                             where n.StartsWith("J")
                             orderby n
                             select n;
            Console.WriteLine("First iteration");
            foreach (string name in namesWithJ)
            {
                Console.WriteLine(name);
            }
            Console.WriteLine();
            names.Add("John");
            names.Add("Jim");
            names.Add("Jack");
            names.Add("Denny");
            Console.WriteLine("second iteration");
            foreach (string name in namesWithJ)
            {
                Console.WriteLine(name);
            }

返回结果如下：

First iteration
Juan

second iteration
Jack
Jim
John
Juan

其他情况：

var names = new List<string> { "Nino o", "Alberto", "Juan", "Mike", "phi1" };
            var namesWithJ = (from n in names
                             where n.StartsWith("J")
                             orderby n
                             select n).ToList();
            Console.WriteLine("First iteration");
            foreach (string name in namesWithJ)
            {
                Console.WriteLine(name);
            }
            Console.WriteLine();
            names.Add("John");
            names.Add("Jim");
            names.Add("Jack");
            names.Add("Denny");
            Console.WriteLine("second iteration");
            foreach (string name in namesWithJ)
            {
                Console.WriteLine(name);
            }