我如何元帅为wchar_t *从C ++到C＃作为out参数或返回值？ [英] How do I marshal wchar_t* from C++ to C# as an out parameter or return value?

问题描述

我试图做到这一点的方法很多，但没有一个是工作。有没有人有一个正确的榜样呢？我只是想从一个函数到C＃的水平移动 wchar_t的* 值。

I have tried to do this in many ways, but none is working. Does anyone have a correct example for this? I just want to move the wchar_t* value from a function to the C# level.

推荐答案

这是不是你认为它是困难...什么是 wchar_t的* ？什么样的价值确实该类型通常重新present？一个字符串。这是等同于 LPWSTR 在 WINDOWS.H 类型来定义。

This isn't as difficult as you think it is... What is wchar_t*? What value does that type typically represent? A string. It's the equivalent to the LPWSTR type defined in windows.h.

所以，你封送它作为一个字符串键入。然而，因为它是一个退出参数（或返回值），你需要使用<一个href="http://msdn.microsoft.com/en-us/library/system.text.stringbuilder.aspx"><$c$c>StringBuilder类 C＃的结束，而不是字符串键入

So, you marshal it as a string type. However, since it's an out parameter (or a return value), you'll need to use the StringBuilder class on the C# end, rather than the string type.

在P / Invoke的语法将是这个样子：

The P/Invoke syntax would look something like this:

[DllImport("MyLib.dll")]
public static extern void MyFunction(StringBuilder str);

和使用它，你首先声明 StringBuiler 类具有适当能力的一个实例，然后调用函数：

And to use it, you first declare an instance of the StringBuiler class with the appropriate capacity, and then call the function:

StringBuilder myString = new StringBuilder(255);
MyFunction(myString);

记住，非托管C ++ code必须释放在字符串中以prevent内存泄漏。它是唯一一个能够访问字符串在何处分配的非托管内存区域。

Remember that the unmanaged C++ code must free the string in order to prevent a memory leak. It's the only one with access to the unmanaged memory area where the string was allocated.

这篇关于我如何元帅为wchar_t *从C ++到C＃作为out参数或返回值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！