blocks|key|5503736|text|Tag是否有名为photoid的成员？也许你需要一个造型来把你的“标签”转换成它应该是的样子？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5503737|++++++++//Tag+tag+=+(Tag)+item.Tag;
++++++++MyObject+tag+=+(MyObject)item.Tag;
++++++++saveSlide(showid,+tag.photoid,+enumber);+
++++++++number%2B%2B;+|code-block|syntax|javascript|5503738|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Does Tag has a member named photoid? Maybe you need a cast in there to convert your 'tag' to whatever it's supposed to be?

<pre><code> //Tag tag = (Tag) item.Tag;
 MyObject tag = (MyObject)item.Tag;
 saveSlide(showid, tag.photoid, enumber); 
 number++; 
</code></pre>

blocks|key|2311167|text|Poppy您正在向listBox1.Items添加title。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2311168|title的类型为string。|2311169|因此，当您访问它时，使用像这样foreach+(string+item+in+listBox1.Items)这样的string类型。|2311170|试试看。有帮助吗？|2311171|++++++++int+number+=+0;
++++++++foreach+(string+item+in+listBox1.Items)
++++++++{
++++++++++++Tag+tag+=+(Tag)+item.Tag;
++++++++++++saveSlide(showid,+tag.photoid,+enumber);
++++++++++++number%2B%2B;
++++++++}|code-block|syntax|javascript|2311172|entityMap^0|9|E|P|5|0|0|5|9|6|0|F|13|1L|6|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|17|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|18|8|@]|D|@]|E|$O|P]]|$1|Q|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|R|$]]

Poppy you are adding <code>title</code> to <code>listBox1.Items</code>. 

<code>title</code> is of type <code>string</code>.

So when you access it use <code>string</code> type like this <code>foreach (string item in listBox1.Items)</code>.

Try. Does it help?

<pre><code> int number = 0;
 foreach (string item in listBox1.Items)
 {
 Tag tag = (Tag) item.Tag;
 saveSlide(showid, tag.photoid, enumber);
 number++;
 }
</code></pre>

blocks|key|403972|text|除非你命名的东西很奇怪，否则我会说错误是你试图从一个ListBox中获取一个ListViewItem。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|403973|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Unless you named things weird I'd say the error is that you're trying to get a ListViewItem from a ListBox.

blocks|key|3392211|text|这是可行的，您需要显示向列表中添加项目的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3392212|private+class+Tag
{
++++public+override+string+ToString()
++++{
++++++++return+"Tag";
++++}
}

ListBox+listBox+=+new+ListBox();
listBox.Items.Add(new+ListViewItem+{+Tag+=+new+Tag()+});
foreach+(ListViewItem+item+in+listBox.Items)
{
++++Tag+tag+=+(Tag)item.Tag;
++++Console.WriteLine(tag);
}|code-block|syntax|javascript|3392213|编辑以下更多代码：|3392214|您正在将字符串而不是ListViewItem添加到ListBox：|3392215|listBox1.Items.Add(title);应为listBox1.Items.Add(item);|offset|length|style|CODE|3392216|entityMap^0|0|0|0|0|0|Q|S|P|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|W|8|@$M|X|N|Y|O|P]|$M|Z|N|10|O|P]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|R|$]]

This works, you need to show the code where you add items to the list:

<pre><code>private class Tag
{
 public override string ToString()
 {
 return "Tag";
 }
}

ListBox listBox = new ListBox();
listBox.Items.Add(new ListViewItem { Tag = new Tag() });
foreach (ListViewItem item in listBox.Items)
{
 Tag tag = (Tag)item.Tag;
 Console.WriteLine(tag);
}
</code></pre>

Edit following more code:

You are adding strings to your ListBox instead of the ListViewItem:

<code>listBox1.Items.Add(title);</code> should be <code>listBox1.Items.Add(item);</code>

blocks|key|3392228|text|ListBox.Items是一个ObjectCollection。这意味着您可以选择要放入其中的对象的类型。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3392229|当你这样做的时候：|3392230|string+title+=+drv["title"].ToString();
listBox1.Items.Add(title);|code-block|syntax|javascript|3392231|您要将string对象放入其中，因此需要像这样将它们取出：|3392232|foreach+(string+item+in+listBox1.Items)|3392233|相反，您可能希望您的代码更像这样：|3392234|ListViewItem+item+=+new+ListViewItem(title);
item.Tag+=+tag;
tag.photoid+=+(int)drv["photoid"];
listBox1.Items.Add(item);+//+The+difference+is+here+-+add+*item*+not+*title*|3392235|然后，您将能够以最初编写的方式使用它：|3392236|foreach+(ListViewItem+item+in+listBox1.Items)|3392237|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.windows.forms.listbox.objectcollection.aspx^0|G|G|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|D|3|E|5|6|7|18|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|19|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|1A|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|1B|8|@]|9|@]|C|$I|J]]|$1|O|3|P|5|6|7|1C|8|@]|9|@]|C|$]]|$1|Q|3|R|5|H|7|1D|8|@]|9|@]|C|$I|J]]|$1|S|3|T|5|6|7|1E|8|@]|9|@]|C|$]]|$1|U|3|V|5|H|7|1F|8|@]|9|@]|C|$I|J]]|$1|W|3|-4|5|6|7|1G|8|@]|9|@]|C|$]]]|X|$Y|$5|Z|10|11|C|$12|13]]]]

ListBox.Items is an <a href="http://msdn.microsoft.com/en-us/library/system.windows.forms.listbox.objectcollection.aspx" rel="nofollow noreferrer">ObjectCollection</a>. That means you can choose the kind of object to put in it.

When you're doing this: 

<pre><code>string title = drv["title"].ToString();
listBox1.Items.Add(title);
</code></pre>

you are putting string objects into it, so you would need to get them out like this:

<pre><code>foreach (string item in listBox1.Items)
</code></pre>

Instead, you probably want your code to be more like this:

<pre><code>ListViewItem item = new ListViewItem(title);
item.Tag = tag;
tag.photoid = (int)drv["photoid"];
listBox1.Items.Add(item); // The difference is here - add *item* not *title*
</code></pre>

then you'll be able to use this the way you initially wrote it:

<pre><code>foreach (ListViewItem item in listBox1.Items)
</code></pre>

blocks|key|3392282|text|只需更改第二个代码片段的最后一行代码，一切都将正常，如下所示。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3392283|3392284|+listBox1.Items.Add(项目)；|blockquote|3392285|3392286|3392287|关于Error的|3392288|您将字符串作为项添加到listBox中，并在前面尝试将一个项(即字符串)隐式地转换(+ListViewItem+)为ListViewItem，这将不起作用，并且编译器会给出错误。|offset|length|style|BOLD|3392289|希望它能起作用。|3392290|entityMap^0|0|0|0|0|0|0|0|2H|0|0|8|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|U|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|V|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|W|8|@]|9|@]|A|$]]|$1|G|3|-4|5|6|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|Z|8|@$L|10|M|11|N|O]]|9|@]|A|$]]|$1|P|3|Q|5|6|7|12|8|@$L|13|M|14|N|O]]|9|@]|A|$]]|$1|R|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|S|$]]

Just change the last line of code of the second code-snippet and everything will be ok, which is as follows.

<blockquote>
 listBox1.Items.Add(item);
</blockquote>

About the Error

You added strings to the listBox as items and in the foreach an item(which is a string) is tried to convert(caste) to ListViewItem implicitly to hich doesn't work and the compiler gives the error.

Hope it will work.

Hi i'm trying to use the tag item of a listbox. 

heres my code.

<pre><code> int number = 0;
 foreach (ListViewItem item in listBox1.Items)
 {
 Tag tag = (Tag) item.Tag;
 saveSlide(showid, tag.photoid, enumber);
 number++;
 }
</code></pre>

problem im havin is when i run the program i get an error message sayin cannot convert type string to system.ListView but i haven't declared item as a string anywher in my program

This is where i add the items to the listbox. Please help. Im on a dead line and have sooo much more to do

<pre><code>private void buttonAdd_Click(object sender, EventArgs e)
{
 //add selected item into listBox
 DataRowView drv = (DataRowView)listBox1.SelectedItem;
 Tag tag = new Tag();
 string title = drv["title"].ToString();
 ListViewItem item = new ListViewItem(title);
 item.Tag = tag;
 tag.photoid = (int)drv["photoid"];

 listBox1.Items.Add(title);
}
</code></pre>

Tag problem c# listbox

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

您好，我正在尝试使用列表框的标记项。这是我的代码。            int number = 0;            foreach (ListViewItem item in listBox1.Items)            {                Tag tag = (Tag) item.T...

问Tag problem c#列表框
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Tag problem c#列表框EN