freeCodeCamp/guide/chinese/csharp/linq/select/index.md

title	localeTitle
Select	选择

选择

从数据集中投射数据。

签名

Enumerable.Select<TSource, TResult> Method (IEnumerable<TSource>, Func<TSource, TResult>) 

例

var fruits = new List<Fruit>() { 
    new Fruit() { Id = 1, Name = "Orange",     Color = "Orange", Quantity = 3   }, 
    new Fruit() { Id = 2, Name = "Strawberry", Color = "Red",    Quantity = 12  }, 
    new Fruit() { Id = 3, Name = "Grape",      Color = "Purple", Quantity = 25  }, 
    new Fruit() { Id = 4, Name = "Pineapple",  Color = "Yellow", Quantity = 1   }, 
    new Fruit() { Id = 5, Name = "Apple",      Color = "Red",    Quantity =  5   }, 
    new Fruit() { Id = 6, Name = "Mango",      Color = "Yellow", Quantity = 2   } 
 }; 
 
 var mangoQnt = fruits.Where(f => f.Name == "Mango").Select(f => f.Quantity).FirstOrDefault(); // 2 
 
 var grapeColor = fruits.Where(f => f.Name == "Grape").Select(f => f.Color).FirstOrDefault(); // Purple