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);

}

}