需要转换String ^到char * [英] Need to convert String^ to char *

问题描述

我使用.NET DateTime获取当前日期和时间。我将它转换为一个字符串，以作为文件名的一部分。问题是用于保存图像的OpenCV命令需要char *而不是字符串类型，并且DateTime将只输出String ^类型。如何使这项工作？尚未完成的代码

I am using the .NET DateTime to get the current date and time. I am converting it to a string to use as part of a file name. The problem is the OpenCV command to save an image requires a char * not a string type, and DateTime will only output a String^ type. How do I make this work? Heres the code not completed

String^ nowString = DateTime::Now.ToString("yyyy-MM-dd-HH:mm");
        IplImage* toSave;
        CvCapture* capture = cvCreateCameraCapture(0);
        toSave = cvQueryFrame( capture );
        cvSaveImage(nowString, toSave);
        cvReleaseImage(&toSave);
        cvReleaseCapture(&capture);

推荐答案

最好的办法是使用 StringToHGlobalAnsi 。下面是完整的代码显示它的完成和记忆释放分配的内存。

Your best bet is to use StringToHGlobalAnsi. Here is complete code showing how its done and remembering to free the memory allocated.

using namespace System::Runtime::InteropServices;

void MethodName()
{
    String^ nowString = DateTime::Now.ToString("yyyy-MM-dd-HH:mm");
    IntPtr ptrToNativeString = Marshal::StringToHGlobalAnsi(nowString);
    try
    {
        CvCapture* capture = cvCreateCameraCapture(0);
        IplImage* toSave = cvQueryFrame(capture);
        cvSaveImage(static_cast<char*>(ptrToNativeString.ToPointer()), toSave);
        cvReleaseImage(&toSave);
        cvReleaseCapture(&capture);
    }
    catch (...)
    {
        Marshal::FreeHGlobal(ptrToNativeString);
        throw;
    }
    Marshal::FreeHGlobal(ptrToNativeString);
}

您可能想使用文件名中的'：'字符重新思考我不相信窗户喜欢这样非常。

You might want to rethink using a ':' character in the filename, as I don't believe windows likes this very much.

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