Win32 LB_GETTEXT 返回垃圾

Win32 LB_GETTEXT returns garbage(Win32 LB_GETTEXT 返回垃圾)

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问题描述

我遇到的问题很可能是一个简单的问题,但对我来说仍然是个问题.我在 Win32/C++ 中使用列表框,当从我的列表框中获取选定的文本时,返回的字符串只是垃圾.它是一个结构或类似的句柄?

I have a problem which is most likely a simple problem, but neverthe less still a problem for me. I am using the Listbox in Win32 / C++ and when getting the selected text from my listbox the string returned is just garbage. It is a handle to a struct or similar?

下面是我得到的代码和示例.

Below is the code and an example of what I get.

std::string Listbox::GetSelected() {
int index = -1;
int count = 0;

count = SendMessage(control, LB_GETSELCOUNT, 0, 0);

if(count > 0) {
    index = SendMessage(control, LB_GETSEL, 0, 0);
}

return GetString(index);
}


std::string Listbox::GetString(int index) {
int count = 0;
int length = 0;
char * text;

if(index >= 0) {
    count = GetItemCount();

    if(index < count) {
        length = SendMessage(control, LB_GETTEXTLEN, (WPARAM)index, 0);
        text = new char[length + 1];

        SendMessage(control, LB_GETTEXT, (WPARAM)index, (LPARAM)text);
    }
}
std::string s(text);
delete[] text;

return s;
}

GetItemCount 就是这样做的.它只是获取当前列表框中的项目数.

GetItemCount just does that. It just gets the number of items currently in the listbox.

我从列表框中获取的字符串是测试字符串",它返回了 ¨±é» Tzã

The string I was grabbing from the Listbox is "Test String" and it returned ¨±é» Tzã

如有任何帮助,谢谢.

好的,我将范围缩小到我的 GetSelected 函数,因为 GetString 返回了正确的字符串.

Ok, I narrowed it down to my GetSelected function as GetString returns the correct string.

推荐答案

LB_GETSEL 消息不返回所选项目的索引,它返回您在 WPARAM 中传递的 ITEM 的所选状态.

The LB_GETSEL message does not return the index of a selected item, it returns the selected STATE of the ITEM you pass in WPARAM.

您还有一个严重的错误,如果没有选择任何项目,您将尝试检索索引 -1 处的项目字符串,这显然是错误的.检查这些 SendMessage 调用的返回值将有助于您诊断问题.

You also have a serious bug where if no items are selected you will attempt to retrieve the string of the item at index -1, which is clearly wrong. Checking the return values of these SendMessage calls would have helped you diagnose the problem.

这里是一个如何获取第一个选中项的文本的示例;

Here's an example of how to get the text of the first selected item;

// get the number of items in the box.
count = SendMessage(control, LB_GETCOUNT, 0, 0);

int iSelected = -1;

// go through the items and find the first selected one
for (int i = 0; i < count; i++)
{
  // check if this item is selected or not..
  if (SendMessage(control, LB_GETSEL, i, 0) > 0)
  {
    // yes, we only want the first selected so break.
    iSelected = i;
    break;
  }
}

// get the text of the selected item
if (iSelected != -1)
  SendMessage(control, LB_GETTEXT, (WPARAM)iSelected , (LPARAM)text);

或者,您可以使用 LB_GETSELITEMS 来获取所选项目的列表.

Alternatively you can use LB_GETSELITEMS to get a list of the items that are selected.

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