illegal use of type name mxArray

Hello,

When I compile the following code, I get an error from the compiler:

        int count_OK;
        double *Gain_final = NULL;
        double *freq_final = NULL;

        // value of count_OK is defined

        Gain_final = (double*)malloc(count_OK*sizeof(double));
        freq_final = (double*)malloc(count_OK*sizeof(double));

        // Fill arrays of variable size Gain_final, phase_final, freq_final

        x_ptr_freq_final = mxCreateDoubleMatrix(1, count_OK, mxREAL);
        memcpy(mxGetPr(x_ptr_freq_final), freq_final, sizeof(double)*count_OK);

        x_ptr_gain_final = mxCreateDoubleMatrix(1, count_OK, mxREAL);
        memcpy(mxGetPr(x_ptr_gain_final), Gain_final, sizeof(double)*count_OK);

        mxArray *prhs[2] = {x_ptr_freq_final, x_ptr_gain_final};

The error of the compiler is the following:

Error time2freq.c: 430  illegal use of type name `mxArray' 
Error time2freq.c: 430  unknown size for type `incomplete struct mxArray_tag defined at C:\Program Files (x86)\Matlab_R2010BSP2\extern\include\matrix.h 298' 
Error time2freq.c: 430  operands of * have illegal types `incomplete struct mxArray_tag defined at C:\Program Files (x86)\Matlab_R2010BSP2\extern\include\matrix.h 298' and `incomplete struct mxArray_tag defined at C:\Program Files (x86)\Matlab_R2010BSP2\extern\include\matrix.h 298' 
Error time2freq.c: 430  illegal expression 
Error time2freq.c: 430  lvalue required 
Warning time2freq.c: 430  possible usage of prhs before definition 
Error time2freq.c: 430  syntax error; found `x_ptr_freq_final' expecting `;' 
Warning time2freq.c: 430  Statement has no effect 
Error time2freq.c: 430  syntax error; found `}' expecting `;' 
Error time2freq.c: 431  illegal use of type name `mxArray'

When the arrays Gain_final and freq_final are not defined dynamically with malloc, everything works. But as the size of these arrays change, I need to use malloc.

Thank you for your help if you have any idea:)

Answer 1

[Jan]

If this is a C-file, definitions of variables must appear before the first command in the function. So try to move "mxArray *prhs[2];" to the top of the function.

[Alex]

Yep, now it works. Thank you :D

[Jan]

Then the error message of the compiler is not useful, although it would be easy to detect the reason of the problem automatically. Shame on the manufacturer of the compiler.