Linq中的Where与SkipWhile

      本文将介绍Linq中的Where与SkipWhile的用法，有时我们容易混淆它们。下面来看一个简单的UnitTest:

[TestMethod]
public void TestSkipWhileAndWhereLinq()
{//arrangestring[] names = { "Jalpesh", "Jayesh", "Tushar", "Tejas", "Sanjay", "Nijesh", "Jemit", "Jay" }; var skipWhileResult = names.SkipWhile(s => s.ToLower().StartsWith("j"));//assertvar expectArray=new string[] { "Tushar", "Tejas", "Sanjay", "Nijesh", "Jemit", "Jay" };CollectionAssert.AreEqual( expectArray, skipWhileResult.ToArray());var whereReuslt = names.Where(s => !s.ToLower().StartsWith("j"));//assertvar expectArray2 = new string[] { "Tushar", "Tejas", "Sanjay", "Nijesh" };CollectionAssert.AreEqual(expectArray2, whereReuslt.ToArray());
}

  SkipWhile只是匹配一开始满足条件的元素。上面的代码一看就明白。更加请参照MSDN

  SkipWhile是这样的实现的:

 

public static IEnumerable SkipWhile(this IEnumerable source, Funcbool> predicate)
{if (source == null) throw Error.ArgumentNull("source");if (predicate == null) throw Error.ArgumentNull("predicate");return SkipWhileIterator(source, predicate);
}private static IEnumerable SkipWhileIterator(IEnumerable source, Funcbool> predicate)
{bool iteratorVariable0 = false;foreach (TSource iteratorVariable1 in source){if (!iteratorVariable0 && !predicate(iteratorVariable1)) iteratorVariable0 = true;if (iteratorVariable0){yield return iteratorVariable1;}}
}

 

  希望对您开发有帮助。 

作者：Petter Liu

出处：http://www.cnblogs.com/wintersun/

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