foreach 语句不能对变量进行操作

Question

我必须上课，Custom Car Factory Class 和 Custom Car Factory，我正在尝试通过使用 foreach 来从定制汽车工厂注销 Custom Car 以获取工厂中的所有数据，但是我收到“foreach”错误语句不能对变量 CustomCarFactory 进行操作，因为 Custom CarFactory 不包含“GetEnumerator”的公共定义”

定制汽车工厂类

[CustomCarFactory.cs]

internal class CustomCarFactory : ICarFactory
public CustomCarFactory(string make, string model, string serial, string plate)
    {
Make = make; 
Model = model;
Serial = serial;
Plate = plate;
}

internal string Make; 
internal string Model; 
internal string Serial; 
internal string Plate; 

Car Library Implementation class
[CarLibraryImplementation.cs]



internal static List<ICarFactory> CarFactories= new List<ICarFactory>(); 

在这部分我将它注册到自定义工厂

private static CustomCarFactory factory = new CustomCarFactory(string.Empty, string.Empty, string.Empty, string.Empty);
 private static void registerCarImplementation(string make, string model, string serial, string plate)
        {
            factory = new CustomCarFactory(make, model, serial, plate);

                CarFactories.Add(factory);

然后在这一部分中，我将从自定义工厂中注销它，但我得到“foreach 语句无法对变量 CustomCarFactory 进行操作，因为 Custom CarFactory 不包含 'GetEnumerator' 的公共定义”

   private static void UnregisterCarImplementation(string make, string model, string serial, string plate)
                {
        foreach (var item in factory)
    {
// Get make from current factory
// Get model from current factory

    }

}

Answer 1

您正在尝试迭代单个项目而不是集合，这就是您收到该错误的原因。

您可以改为迭代 CarFactories 集合：

private static void UnregisterCarImplementation(
    string make, string model, string serial, string plate)
{
    foreach (var item in CarFactories)
    {
        if (item.Make == make && item.Model == model
            && item.Serial == serial && item.Plate == plate)
        {
            // take some action
        }
    }
}

或者您可以使用集合可用的RemoveAll 方法：

private static void UnregisterCarImplementation(
    string make, string model, string serial, string plate)
{
    CarFactories.RemoveAll(x => x.Make == make && x.Model == model
                                && x.Serial == serial && x.Plate == plate);
}