将变量从C ++传递到Matlab（工作空间） [英] Passing Variable from C++ to Matlab (Workspace)

问题描述

我试图传递一个变量 z = 100 从C ++到Matlab进一步处理（这只是一个非常简化的例子）。我基本上希望这可以作为一个全局变量传递，这样我可以从任何Matlab函数访问这个变量（也许发送到Matlab工作区）。

这是我的C ++代码（我在C ++中使用Matlab引擎）：

  #includeopencv2 / highgui / highgui.hpp 
 #includeopencv2 / opencv.hpp
 #include< iostream> 
 #include< math.h> 
 #include< fstream> 
 #include< stdio.h> 
 #include< Windows.h> 
 #includeengine.h
 #include< engine.h> 
 //＃include< cmath> 
 #define _USE_MATH_DEFINES 
 
 #pragma comment（lib，libmat.lib）
 #pragma comment（lib，libmx.lib）
 #pragma comment （lib，libmex.lib）
 #pragma comment（lib，libeng.lib）
 
 using namespace cv; 
 using namespace std; 
 
 int main（int argc，char * argv []）
 {
 Engine * ep = engOpen（NULL）; 
 int z; 
 mxArray * z_array = mxCreateDoubleMatrix（1,1，mxREAL）; 
 double * pz = mxGetPr（z_array）; 
 z = 100; 
 engPutVariable（ep，z，z_array）; 
 
 engClose（ep）; 
 
 return 0; 
} 
  

当这段代码执行完毕后，我打开Matlab并尝试访问变量 z ，但它不存在。有没有什么我在这里失踪？ （我也试过在后插入 engEvalString（ep，global z; disp（z）;）; engPutVariable

=h2_lin>解决方案

您的代码对我看起来不错
通过writng engClose（ep）;关闭Matlab引擎，使得变量z将随着Matlab会话消失。 p>

编辑：通过检查你的代码，我注意到z没有受到z_array的影响，所以试试下面的代码

  mxArray * z_array = NULL; 
 double z [1] = {100}; 
 z_array = mxCreateDoubleMatrix（1,1，mxREAL）; 
 memcpy （b * b）
（b * b）
（b * b）
  

I'm trying to pass a variable z = 100 from C++ to Matlab for further processing (this is just a very simplified example). I basically want this to be passed as a global variable such that I can access this variable from any Matlab function, (perhaps sent to the Matlab Workspace).

Here is my C++ code (I'm using the Matlab engine from within C++):

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/opencv.hpp"
#include <iostream>
#include <math.h>
#include <fstream>
#include <stdio.h>
#include <Windows.h>
#include "engine.h"
#include <engine.h>
//#include <cmath>
#define _USE_MATH_DEFINES

#pragma comment ( lib, "libmat.lib" )
#pragma comment ( lib, "libmx.lib" )
#pragma comment ( lib, "libmex.lib" )
#pragma comment ( lib, "libeng.lib" )

using namespace cv;
using namespace std;

int main (int argc, char* argv[])
{
    Engine *ep = engOpen(NULL);
    int z;
    mxArray *z_array = mxCreateDoubleMatrix(1,1,mxREAL);
    double *pz = mxGetPr(z_array);
    z = 100;
    engPutVariable(ep, "z", z_array);

    engClose(ep);

    return 0;
}

When this code has finished executing, I open Matlab and try to access the variable z but it doesn't exist. Is there something I'm missing here? (I've also tried inserted engEvalString(ep, "global z; disp(z);"); after engPutVariable but this doesn't help.

I'd appreciate any insight you might be able to give me. Thanks!

解决方案

Your code looks good to me. By writng engClose(ep); you close the Matlab Engine so the variable z will disappear with the Matlab session.

EDIT : By reviewing your code, I noticed that z has not been affected to z_array. So try the following code

mxArray *z_array = NULL;
double z[1] = {100};
z_array = mxCreateDoubleMatrix(1, 1, mxREAL);
memcpy((char *) mxGetPr(z_array), (char*) z, sizeof(double));
engPutVariable(ep, "z", z_array);
mxDestroyArray(z_array);

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