帮助将foreach循环转换为c#中的while循环

Question

我在这里通过阅读你的好答案来学习,从foreach循环中删除项目并不是一个好习惯,因为它是(并且我引用)"锯掉你所坐的分支".

我的代码当前从下拉列表中删除了文本,但实际项目仍然存在(仅显示文本).

换句话说,它不是删除,也可能是因为你无法从foreach循环中删除.

经过几个小时的尝试,我无法理解这种做法.

//For each checked box, run the delete code
for (int i = 0; i < this.organizeFav.CheckedItems.Count; i++)
{
    //this is the foreach loop
    foreach (ToolStripItem mItem in favoritesToolStripMenuItem.DropDownItems)
    {
        //This rules out seperators
        if (mItem is ToolStripMenuItem)
        {
            ToolStripMenuItem menuItem = mItem as ToolStripMenuItem;

            //This matches the dropdownitems text to the CheckedItems String
            if (((ToolStripMenuItem)mItem).Text.ToString() == organizeFav.CheckedItems[i].ToString())
            {
                //And deletes the item
                menuItem.DropDownItems.Remove(mItem);
            }
        }
    }
}

但它并没有删除,因为它在foreach循环中!我非常感谢您的帮助,如果有人能够了解这些代码,我会感到非常惊讶:)

亲切的问候

Answer 1

LINQ的乐趣!

// Loop through the checked items, same as you did.
foreach (var checkedItem in this.organizeFav.CheckedItems)
{
    // Cast from IEnumerable to IEnumerable<T> so we can abuse LINQ
    var matches = favoritesToolStripMenuItem.DropDownItems.Cast<ToolStripItem>()
                  // Only items that the Text match
                  .Where(item => item.Text == checkedItem.Text)
                  // Don't match separators
                  .Where(item => item is ToolStripMenuItem)
                  // Select the keys for the later .Remove call
                  .Select(item => item.Name);

    // Loop through all matches        
    foreach (var key in matches)
    {
        // Remove them with the Remove(string key) overload.
        favoritesToolStripMenuItem.Remove(key);
    }
}