安全地删除DataRow在ForEach [英] Safely Removing DataRow In ForEach

问题描述

我不明白为什么这段代码不起作用。

I don't understand why this code does not work.

foreach (DataRow dataRow in dataTable.Rows)
{
    if (true)
    {
        dataRow.Delete();
    }
}

推荐答案

.NET中的集合不允许您在迭代时更改集合的内容。从文档 IEnumerator ：

Most collections in .NET don't allow you to change the contents of the collection while you're iterating over it. From the docs for IEnumerator:

只要
，枚举器仍然有效，集合保持不变。如果
更改为集合，
，如添加，修改或删除
元素，枚举器是
不可恢复地无效，下一个
调用MoveNext或重置抛出
InvalidOperationException。如果
集合在
MoveNext和Current之间被修改，Current将返回
它被设置为的元素，即使
枚举器已经无效。

An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and the next call to MoveNext or Reset throws an InvalidOperationException. If the collection is modified between MoveNext and Current, Current returns the element that it is set to, even if the enumerator is already invalidated.

最好的解决方案通常是创建一个单独的集合（例如 List< DataRow> ）项目您要删除，然后在完成迭代后将其移除

The best solution is usually to create a separate collection (e.g. a List<DataRow>) of items you want to remove, and then remove them after you've finished iterating.

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