mex C struct pointer

how can i use mex function return a structer pointer to matlab？is there any possbile for mex function return a pointer？as i know mexfunction just can return a double *

like this is a structer in C，can i return a pointer which point to this structer in mex function？

Answer 1

[俊凯 王]

use intptr_t ，i got it

code like this

pointer_return.cpp

#include "mex.h"

#include "matrix.h"

struct test

{

struct test* left;

struct test* right;

int id;

};

void mexFunction(int nlhs, mxArray * plhs[], int nrhs, const mxArray * prhs[]){

struct test* root = (test*)malloc(sizeof(test));

struct test* root_left = (test*)malloc(sizeof(test));

struct test* root_right = (test*)malloc(sizeof(test));

root_right->left = nullptr;//这个必须赋值为空值指针，不赋值的话访问不了

root_right->right = nullptr;

root_left->right = nullptr;

root_left->left = nullptr;

root->id = 0; root_left->id = 1; root_right->id = 2;

root->left = root_left;

root->right = root_right;

plhs[0] = mxCreateDoubleMatrix(1,1,mxREAL);

double* pointer_to_tree = mxGetPr(plhs[0]);

pointer_to_tree[0] = (intptr_t) root;

}

change_intopointer.cpp

#include "mex.h"

#include "matrix.h"

struct test

{

struct test* left;

struct test* right;

int id;

};

void mexFunction(int nlhs, mxArray * plhs[], int nrhs, const mxArray * prhs[]){

double* root_double = mxGetPr(prhs[0]);

intptr_t pointer1 = (intptr_t) root_double[0];

struct test *test_root = (struct test*) pointer1;

mexPrintf("root id is %d\n",test_root->id);

mexPrintf("left id is %d\n",test_root->left->id);

mexPrintf("right id is %d\n",test_root->right->id);

}

matlab.m

tic

root=pointer_return();

toc

tic

change_intopointer(root)

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