将void *转换为std :: string [英] Converting a void* to a std::string

问题描述

在浏览网页和搞乱自己后，我似乎无法将void *的目标（这是一个字符串）转换为std :: string。我尝试使用 sprintf（buffer，％p，*（（int *）point））; .daniweb.com / forums / thread221261.html>此页面获取C字符串，但无效。很遗憾，是的，我必须使用void *，因为这是SDL在USEREVENT结构中使用的。

After perusing the web and messing around myself, I can't seem to convert a void*'s target (which is a string) to a std::string. I've tried using sprintf(buffer, "%p", *((int *)point)); as recommended by this page to get to a C string, but to no avail. And sadly, yes, I have to use a void*, as that's what SDL uses in their USEREVENT struct.

我用来填充Userevent的代码那些感兴趣的是：

The code I'm using to fill the Userevent, for those interested, is:

std::string filename = "ResumeButton.png";
SDL_Event button_press;
button_press.type = BUTTON_PRESS;
button_press.user.data1 = &filename;
SDL_PushEvent(&button_press);

任何想法？

对于所有的响应，我只需要将void *转换为std :: string *。我傻。非常感谢你们！

Thanks for all the responses, I just needed to cast the void* to a std::string*. Silly me. Thank you guys so much!

推荐答案

你只需要动态分配它（因为它可能需要超出你的范围使用它），然后来回转换：

You just need to dynamically allocate it (because it probably needs to outlive the scope you're using it in), then cast it back and forth:

// Cast a dynamically allocated string to 'void*'.
void *vp = static_cast<void*>(new std::string("it's easy to break stuff like this!"));

// Then, in the function that's using the UserEvent:
// Cast it back to a string pointer.
std::string *sp = static_cast<std::string*>(vp);
// You could use 'sp' directly, or this, which does a copy.
std::string s = *sp;
// Don't forget to destroy the memory that you've allocated.
delete sp;

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