如何以编程方式从 DataTable 中删除 DataColumn [英] How to remove DataColumn from DataTable programmatically

问题描述

我有一个代码

foreach (DataColumn dataTableCol in this.dataTable.Columns)
            {
                bool columnFound = false;
                foreach (GRTColumnView uiColumn in descriptor.UIColumns)
                {
                    if (dataTableCol.ColumnName.Equals(uiColumn.Name))
                    {
                        columnFound = true;
                        break;
                    }
                }

                if (!columnFound)
                {
                    if (this.dataTable.Columns.Contains(dataTableCol.ColumnName))
                        this.dataTable.Columns.Remove(dataTableCol.ColumnName);
                }

            }

如果在另一个集合中找不到某些东西"，我想从集合中删除它们.

I want to remove some "things" from collection if they aren't found in another collection.

当我运行上面的程序时，我得到

When I run the above program, I get

由于集合被修改，迭代可能无法执行

集合已修改" - 因为删除必须被点击

"Collection was modified" - Coz the remove must have been hit

那么有什么方法可以实现这样的事情?

我能想到的就是记下所有要删除的东西"，然后

What I can think of is make a note of all the "things" to remove and then

foreach( aThing in all_things_to_remove)
     remove_from_collection(aThing)

但以上对我来说似乎不是一个好方法，因为我必须进行另一个循环并且正在使用额外的内存

But above doesn't seem a good way to me, as I have to do another looping and am using extra memory

推荐答案

在这种特定情况下，当您遍历一个包含几列的小集合时，您只需创建一个新集合(通过 ToList())，这样你就不会迭代你正在修改的同一个集合:

In this specific case, where you're looping through a small collection containing a few columns, you can just create a new collection (via ToList()), so that you're not iterating over the same collection you're modifying:

foreach (var dataTableCol in dataTable.Columns.Cast<DataColumn>().ToList())
{
    ...

    dataTable.Columns.Remove(dataTableCol.ColumnName);
}

推荐的方法是向后枚举，尤其是在集合很大的情况下:

The recommended way, especially if the collection is large, is to enumerate backwards:

for (var i = dataTable.Columns.Count - 1; i >= 0; i--)
{
    ...

    dataTable.Columns.Remove(dataTable.Columns[i].ColumnName);
}

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