c# - C# Foreach 语句不包含 GetEnumerator 的公共定义

Question

我在使用 C# 构建的 Windows 窗体应用程序时遇到问题。错误说明“foreach 语句无法对 'CarBootSale.CarBootSaleList' 类型的变量进行操作，因为 'CarBootSale.CarBootSaleList' 不包含 'GetEnumerator' 的公共定义”。

我似乎无法理解是什么原因造成的。

这是引发错误的代码：

        List<CarBootSaleList> Sortcarboot = new List<CarBootSaleList>();

        foreach (CarBootSale c in carBootSaleList)
        {
            if (c.Charity == "N/A")
            {
                Sortcarboot.Add(carBootSaleList);
                textReportGenerator.GenerateAllReport(Sortcarboot, AppData.CHARITY);
            }
        }

这是 CarBootSaleList 类，它说没有 GetEnumerator 定义：

public class CarBootSaleList
{

    private List<CarBootSale> carbootsales;

    public CarBootSaleList()
    {
        carbootsales = new List<CarBootSale>();
    }

    public bool AddCarBootSale(CarBootSale carbootsale)
    {
        bool success = true;
        foreach (CarBootSale cbs in carbootsales)
        {
            if (cbs.ID == carbootsale.ID)
            {
                success = false;
            }
        }
        if (success)
        {
            carbootsales.Add(carbootsale);
        }
        return success;
    }

    public void DeleteCarBootSale(CarBootSale carbootsale)
    {
        carbootsales.Remove(carbootsale);
    }

    public int GetListSize()
    {
        return carbootsales.Count();
    }

    public List<CarBootSale> ReturnList()
    {
        return carbootsales;
    }

    public string Display()
    {
        string msg = "";

        foreach (CarBootSale cbs in carbootsales)
        {
            msg += String.Format("{0}  {1}", cbs.ID, cbs.Location, cbs.Date);
            msg += Environment.NewLine;
        }
        return msg;
    }

score 22 · Accepted Answer

Your CarBootSaleList class is not a list. It is a class that contain a list.

You have three options:

Make your CarBootSaleList object implement IEnumerable

or

make your CarBootSaleList inherit from List<CarBootSale>

or

if you are lazy this could almost do the same thing without extra coding

List<List<CarBootSale>>

score 18 · Accepted Answer

您没有向我们展示carBootSaleList. 但是，从异常消息中我可以看到它的类型为CarBootSaleList. 此类型不实现IEnumerable接口，因此不能在 foreach 中使用。

你的CarBootSaleList班级应该实现IEnumerable<CarBootSale>：

public class CarBootSaleList : IEnumerable<CarBootSale>
{
    private List<CarBootSale> carbootsales;

    ...

    public IEnumerator<CarBootSale> GetEnumerator()
    {
        return carbootsales.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return carbootsales.GetEnumerator();
    }
}

score 4 · Accepted Answer

在foreach循环中而不是carBootSaleList使用carBootSaleList.data.

您可能不再需要答案，但它可以帮助某人。

score 1 · Accepted Answer

You should implement the IEnumerable interface (CarBootSaleList should impl it in your case).

http://msdn.microsoft.com/en-us/library/system.collections.ienumerable.getenumerator.aspx

But it is usually easier to subclass System.Collections.ObjectModel.Collection and friends

http://msdn.microsoft.com/en-us/library/system.collections.objectmodel.aspx

Your code also seems a bit strange, like you are nesting lists?

c# - C# Foreach 语句不包含 GetEnumerator 的公共定义

4 回答 4

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