C#错误集合已修改；枚举操作可能无法执行 [英] C# error Collection was modified; enumeration operation might not execute

问题描述

下面是我正在调用的代码，并且正在发生异常.集合已修改；枚举操作可能无法执行.

Below is my code which am calling and am getting below exception. Collection was modified; enumeration operation might not execute.

在此代码中，检查数据集是否包含tb_error表名称，然后检查行数.如果rowcount> 1，则插入db.之后，我想清除该表，然后再清除其他视图.请帮助我在哪里修改我的代码.

In this code am checking if dataset contains tb_error table name and then checking the row count. If rowcount> 1 , insert into db. after that i want to clear that table and after that i need to clear other view also. Please help me where to modify my code.

    if (MainClass.OutputDataset.Tables.Contains(tb_error.TableName))
         {
             foreach (DataRow drErr in MainClass.OutputDataset.Tables[tb_error.TableName].Rows)
             {
                 //insert into DB
             }
         }

        if (MainClass.OutputDataset != null && MainClass.OutputDataset.Tables["tb_error"].Rows.Count > 0)
        {
            MainClass.OutputDataset.Tables["tb_error"].Clear();
        }

        MainClass.dsinput.Tables.Remove("BSData_VW");               
        }

推荐答案

之所以会发生这种情况，是因为此基础集合已经添加或删除了项，从而使循环无效.

This happens because the underlying collection has since had items added or removed, which invalidates the loop.

您可以通过拍摄快照来解决此问题，例如:

You can get around this by taking a snapshot, e.g.:

foreach (DataRow drErr in MainClass.OutputDataset.Tables[tb_error.TableName].Rows.ToList())
{
   //insert into DB
}

关键是最后一个 .ToList()调用，这意味着foreach循环仅在时间点上对 Rows 进行操作.

The key is the .ToList() call at the end, which means the foreach loop only operates on Rows as it is at the point-in-time.

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