使用迭代器遍历文件信息的详解

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我是靠谱客的博主自信乌冬面，最近开发中收集的这篇文章主要介绍使用迭代器遍历文件信息的详解，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1.迭代文件的行

复制代码代码如下:

        public static IEnumerable<string> ReadLines(string fileName)
        {
            using (TextReader reader = File.OpenText(fileName))
            {
                string line;
                if ((line = reader.ReadLine()) != null)
                {
                    yield return line;
                }
            }
        }
        static void Main()
        {
            foreach (string line in Iterator.ReadLines(""))
            {
                Console.WriteLine(line);
            }
        }

2.使用迭代器和谓词对文件中的行进行筛选

复制代码代码如下:

       public static IEnumerable<T> where<T>(IEnumerable<T> source, Predicate<T> predicate)
        {
            if (source == null || predicate == null)
            {
                throw new ArgumentNullException();
            }
            return WhereImplemeter(source, predicate);
        }
       private static IEnumerable<T> WhereImplemeter<T>(IEnumerable<T> source, Predicate<T> predicate)
        {
            foreach (T item in source)
            {
                if (predicate(item))
                {
                    yield return item;
                }
            }
        }
        static void Main()
        {
            IEnumerable<string> lines = File.ReadAllLines(@"your file name");
            Predicate<string> predicate = delegate(string line)
            {
                return line.StartsWith("using");
            };
            foreach (string str in where(lines, predicate))
            {
                Console.WriteLine(str);
            }

        }