使用LINQ更改集合中的项目

Question

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");

或这个:

for (var item in allCars.Select(c => c.Model == "Colt"))
{
    item.Model = "Dart";
}

或这个:

allCars.Single(c => c.Model == "Colt").Model = "Dart";

但是如何在列表中"就地"修改项目呢？

如果我有一个要修改的属性,我提到的最后一种方法可以正常工作,但如果我有两个属性怎么办？

Answer 1

LINQ是一种查询语言,它应该保持原始集合不可变.

还行吧

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