如何在 C# 中迭代​​时修改或删除可枚举集合中的项目 [英] How to modify or delete items from an enumerable collection while iterating through it in C#

问题描述

我必须从数据表中删除一些行.我听说在迭代时更改集合是不行的.因此，我应该先遍历数据表并添加列表中的所有行，然后遍历列表并标记用于删除的行.造成这种情况的原因是什么，我有哪些替代方案(而不是使用行列表)?

I have to delete some rows from a data table. I've heard that it is not ok to change a collection while iterating through it. So instead of a for loop in which I check if a row meets the demands for deletion and then mark it as deleted, I should first iterate through the data table and add all of the rows in a list, then iterate through the list and mark the rows for deletions. What are the reasons for this, and what alternatives do I have (instead of using the rows list I mean)?.

推荐答案

如果您使用简单的 for 循环，您可以从集合中删除元素.

You can remove elements from a collection if you use a simple for loop.

看看这个例子:

        var l = new List<int>();

        l.Add(0);
        l.Add(1);
        l.Add(2);
        l.Add(3);
        l.Add(4);
        l.Add(5);
        l.Add(6);

        for (int i = 0; i < l.Count; i++)
        {
            if (l[i] % 2 == 0)
            {
                l.RemoveAt(i);
                i--;
            }
        }

        foreach (var i in l)
        {
            Console.WriteLine(i);
        }

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