我有以下代码:
List<Car> allCars = new List<Car>
{
new Car(1977, "Ford", "Pinto"),
new Car(1983, "Ford", "Taurus"),
new Car(1981, "Dodge", "Colt"),
new Car(1982, "Volkwagen", "Scirocco"),
new Car(1982, "Dodge", "Challenger")
};
Array.ForEach(allCars.ToArray(), Console.WriteLine);
// I want to do an "in-place" modification of an item in
// the list
var query = allCars.Select(x =>
{
if (x.Model == "Colt") return "Dart";
});
public class Car
{
public int Year { get; set; }
public string Make { get; set; }
public string Model { get; set; }
public Car(int year, string make, string model)
{
Year = year; Make = make; Model = model;
}
public override string ToString()
{
return string.Format("{0} - {1} {2}", Year, Make, Model);
}
}
现在我知道我可以这样做:
var query = allCars.Select(c => c.Model == "Colt");
或者这个:
for (var item in allCars.Select(c => c.Model == "Colt"))
{
item.Model = "Dart";
}
或者这个:
allCars.Single(c => c.Model == "Colt").Model = "Dart";
但是,如何修改列表中的"就地"项?
如果我有一个属性要修改,我提到的最后一种方法可以正常工作,但是如果我有两个属性怎么办?
LINQ 是一种查询语言,它应该保持原始集合不可变。
这没关系
foreach (var item in allCars.Where(c => c.Model == "Colt"))
{
item.Model = "Dart";
}
请阅读这篇文章,了解为什么它没有在 LINQ 中实现
foreach(var item in allCars.Where(c => c.Model == "Colt"))
{
item.Model = "Dart";
}