转换对象的列表从一种类型到另一个使用lambda表达式 [英] convert a list of objects from one type to another using lambda expression

问题描述

我有一个foreach循环读取一种类型的对象的列表，并产生一个不同类型的对象的列表。我被告知，一个lambda表达式可以达到同样的效果。

I have a foreach loop reading a list of objects of one type and producing a list of objects of a different type. I was told that a lambda expression can achieve the same result.

var origList = List<OrigType>(); // assume populated
var targetList = List<TargetType>(); 

foreach(OrigType a in origList) {
    targetList.Add(new TargetType() {SomeValue = a.SomeValue});
}

任何帮助将是appreciated-我是新来的lambda和LINQ
感谢，
S

Any help would be appreciated- i'm new to lambda and linq thanks, s

推荐答案

请尝试以下

var targetList = origList
  .Select(x => new TargetType() { SomeValue = x.SomeValue })
  .ToList();

这是使用Lambda表达式和LINQ的组合来实现该解决方案。选择功能是将原来的集合中应用传递委托（或lambda在这种情况下）的每一个值的投影式的方法。其结果将在一个新的返回的IEnumerable<&的TargetType GT; 。该.ToList调用是一个扩展方法，将它转换的IEnumerable< TargetType的> 到列表< TargetType的> 。

This is using a combination of Lambdas and LINQ to achieve the solution. The Select function is a projection style method which will apply the passed in delegate (or lambda in this case) to every value in the original collection. The result will be returned in a new IEnumerable<TargetType>. The .ToList call is an extension method which will convert this IEnumerable<TargetType> into a List<TargetType>.

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