首页 \ 问答 \ 来自非管理世界的C＃结构能否“实时” - 更新？(Can C# structs coming from the unmanaged world be “live”-updating?)

来自非管理世界的C＃结构能否“实时” - 更新？(Can C# structs coming from the unmanaged world be “live”-updating?)

 假设我从非托管库获取一个指向结构的IntPtr指针。 有没有办法，在C＃中，从这个指针获取一个“实时”结构，这样如果我做一个修改非托管结构的调用，我的“实时”结构会立即反映出来吗？  
 我相信标准方法是使用编组来构造数据的副本，由于各种原因（结构布局，数据类型兼容性，不驻留在.NET托管内存中），这样就不能像这样“实时”。 但我找不到任何明确的确认，在C＃中不可能使用“实时”结构。 是吗？  
 在没有使用C ++ / CLI的情况下，我最接近这种“实时”结构的是什么？ 

Suppose I get an IntPtr pointer to a struct from an unmanaged library. Is there any way, in C#, to obtain a "live" struct from this pointer, so that if I make a call that modifies the unmanaged struct, my "live" struct reflects this immediately? 
I believe the standard approach is to construct a copy of the data using marshalling, which can't be "live" like this for various reasons (struct layout, data type compatibility, not residing in the .NET managed memory). But I couldn't find any explicit confirmation that "live" structs are impossible in C# though. Are they? 
What's the closest I can get to such "live" structs without going to C++/CLI?

原文：https://stackoverflow.com/questions/7956355

更新时间：2022-01-07 08:01

最满意答案

 http://developer.android.com/reference/android/os/AsyncTask.html 。 查看标题The 4 steps下的主题。  
 您正在获取Toast的NullPointerException。 如果你从MainActivity调用asynctask那么  
 尝试  
  Toast.makeText(MainActivity.this, "Podaci uspešno preuzeti", Toast.LENGTH_SHORT).show();
 
 您应该将活动上下文，文本和持续时间作为参数传递给makeText。  
                                   OR
 
 根据Eng.Fouad的建议，你的dl为null。 

http://developer.android.com/reference/android/os/AsyncTask.html. Look at the topic under heading The 4 steps. 
You are getting NullPointerException for the Toast. If you calling asynctask from say MainActivity then  
Try 
  Toast.makeText(MainActivity.this, "Podaci uspešno preuzeti", Toast.LENGTH_SHORT).show();
 
Your should pass activity context,your text and duration as parameters to makeText. 
                                   OR
 
As suggested by Eng.Fouad your dl is null.

来自非管理世界的C＃结构能否“实时” - 更新？(Can C# structs coming from the unmanaged world be “live”-updating?)

最满意答案

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