Question

The code which executed prompts to error is:

 void mexFunction(int nlhs,mxArray *plhs[],int nrhs,const mxArray *prhs[])
 {
    double p;
    p  =   (double)mxGetScalar(prhs[0]);
    mexCallMATLAB(0,NULL,1, prhs, "clear");

 }

Where I am trying to clear a variable which is in workspace pointed by prhs[0].
Please suggest what am I doing wrong.

Error message when executed this function with one argument. gives following error message:

callmatlabtest(10)
??? Error using ==> clear
Argument must contain a string.

Answer 1

I believe you need to have &prhs[0] in your call:

mexCallMATLAB(0, NULL, 1, &prhs[0], "clear"); 

I’ve tested this code and it works (in a file named mextest.c):

#include "mex.h"
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
  mexCallMATLAB(0,NULL,1, &prhs[0], "clear");
}

and here is the result:

>> a = 10;
>> who
Your variables are:
a  
>> mextest('a')
>> who
>>