Transmit a Structure from MATLAB to C

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Ziyu Hua
Ziyu Hua 2022-1-19
评论： James Tursa 2022-1-19
Hello everyone. I want to transmit a MATLAB structure to C. Like:
a.para1=1;
a.para2=2;
...
In my C code, I want to use these parameters to do my futher work. The current code I used is
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
double *pointerlhs, *pointerrhs[2]; /* pointer to real data in new array */
mwSize index;
/* Check for proper number of arguments. */
if (nrhs != 1) {
mexErrMsgTxt("This function takes one input arguments.");
}
/* Create an m-by-n mxArray; you will copy existing data into it */
plhs[0] = mxCreateNumericMatrix(1, 2, mxDOUBLE_CLASS, mxREAL);
//pointerrhs[1] = mxGetPr(prhs[0]);
pointerlhs = mxGetPr(plhs[0]);
/* Copy data into the mxArray */
for (index = 0; index < 2; index++) {
pointerrhs[index]= mxGetPr(prhs[index]);
pointerlhs[index] = *pointerrhs[index];
}
return;
}
which meed to tramsmit the value of the structure one by one like:
Transmit_Function(a.para1,a.para2...)
How can I get all parameters in a structure while just use one input in my MATLAB code. Like:
Transmic_Function(a)
Then I can get and use all the paramters in a.
Thanks.

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采纳的回答

Ziyu Hua
Ziyu Hua 2022-1-19
This can be realized by MATALB C API function "mxGetField"
#if !defined(_WIN32)
#define dgesv dgesv_
#endif
#include "mex.h"
#include"matrix.h"
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
if (mxIsStruct(prhs[0]))
{
double *pointer, *pointerrhs;
mxArray *StructValue = mxGetField(prhs[0], 0, "a");
plhs[0] = mxCreateNumericMatrix(1, 1, mxDOUBLE_CLASS, mxREAL);
pointer = mxGetPr(plhs[0]);
pointer[0] = *(mxGetPr(StructValue));
}
else
{
mexErrMsgTxt("The Input is Not a Struct");
}
}
  1 个评论
James Tursa
James Tursa 2022-1-19
This will not work. The variable name is "a", but the field names are "para1" and "para2". You need to use the field names in your mxGetField( ) call, not "a". Also your code is overly complicated and does not contain argument checking so it will crash with invalid inputs.

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