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1.对查询结果进行转换。

string[] names={
   "ADE","Jerry","Steves"};var ns=from s in names            where  s.StartWiths("A")            Select   s.ToLower();foreare(var o  in na){        Console.WriteLine(o);}　　

2. 对于数组，select可以对数组元素以及索引进行操作：

string[] names = { "Jack", "Bob", "Bill", "Catty", "Willam" };  var rs = names.Select((name, index) => new { Name = name, Index = index });  foreach (var r in rs)      Console.WriteLine(r);

3. 对于集合（wpf中的mvvm为例子），查询选中项是否符合要求：

private const string LMPPropertyName="LMPSource";private OberservableCollection
     
       _LMPSource;public  OberservableCollection
      
         LMPSource{get{
   return _LMPSource;}set{if(_LMPSource==value)     return;RaisePropertyChanging(LMPPropertyName);_LMPSource==value;RaisePropertyChanged(LMPPropertyName);}}int a=LMPSource.Select((s,index)=>new{s,index}).FirstOrDefault(w=w.s==LMPSource.Where(e=>e.ZT!="0").FirstOrDefault()).index+1;Console.WriteLine(a)
      
     

4. 组合查询，可以对多个数据源进行组合条件查询（相当于使用SelectMany函数），下面的例子其实就相对于一个双重循环遍历：

int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };    int[] numbersB = { 1, 3, 5, 7, 8 };    var pairs =        from a in numbersA,                b in numbersB        where a < b        select new {a, b};    Console.WriteLine("Pairs where a < b:");    foreach (var pair in pairs)        Console.WriteLine("{0} is less than {1}", pair.a, pair.b);

 

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