how to run c program file in matlab

Hi i wish to call function written in .c in matlab. I installed sdk. I tried with mex filename.c and got the following error

C:\Users\Deepa\Documents\MATLAB\treevalc.c(26) : warning C4101: 'cid' : unreferenced local variable
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(92) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(94) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(95) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(97) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(100) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(101) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(102) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(104) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(105) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(105) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(105) : error C2065: 'nsplits' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(105) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(106) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(110) : error C2065: 'ncatsplit' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(110) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(110) : error C2109: subscript requires array or pointer type
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(111) : error C2065: 'catsplit' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(111) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(111) : error C2109: subscript requires array or pointer type
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(114) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(115) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(119) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(121) : error C2065: 'numdata' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(122) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(125) : error C2143: syntax error : missing ';' before 'type'
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(126) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(126) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(126) : error C2065: 'numdata' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(126) : error C2065: 'n' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(127) : error C2065: 'var' : undeclared identifier
  C:\Users\Deepa\Documents\MATLAB\treevalc.c(127) : warning C4047: 'function' : 'int *' differs in levels of indirection
  from 'int'

I am able to call successfully .cpp file in matlab but getting error while using .c file. I am using windows 10 matlab r2014a.

[KSSV]

https://in.mathworks.com/help/simulink/slref/coder.ceval.html

[Walter Roberson]

Can you attach the .c ? You may need to zip it and attach that.

[SHOBA MOHAN]

Thanks for the answer. I tired with that and got invalid option. I am intended to use the c program function into matlab. For your reference i am attaching my .c file code. Please suggest the way forward

#include "mex.h"
#include <stdlib.h>
#include <stdio.h>
/** 
 * Return the decision tree node corresponding to the given value set
 *
 * var[n]: the attribute ids for node n
 * cut[n]: the threshold value for node n
 * left_child[n]: the node id of the left child of node n, 0 if node n is terminal
 * right_child[n]: the node id of the right child of node n, 0 if node n is terminal
 * ncatsplit[c]: the number of values resulting in a left branch
 * catsplit[c]: the values that would result in a left branch
 * attributes: the attribute (variable) values for each feature
 **/
void
treevalc(int* var, double* cut, int* left_child, int* right_child, 
   int* ncatsplit, double** catsplit, 
   double* attributes,
   int* node_id) {

    int currnode = 0;

    int nextnode;
    int currvar;
    double currval;
    int cid, v;
    int numvals;
    double* vals;

    /*  printf("init nodes: %d  %d  \n", left_child[currnode], right_child[currnode]); */

    /* until reached terminal node */
    while ((left_child[currnode] != 0) && (right_child[currnode] != 0)) {

      /*printf("currnode: %d\n", currnode);*/

      nextnode = -1;

      currvar = abs(var[currnode])-1;
      currval = attributes[currvar];

      /* decision based on thresholded float value */
      if (var[currnode] > 0) {

        /*printf("currvar: %d\n", currvar);*/

        /* branch left */
        if (currval < cut[currnode]) {
    nextnode = left_child[currnode];
        }
        /* branch right */
        else {
    nextnode = right_child[currnode];
        }      
      }
      /* decision based on discrete value */
      else {
        numvals = ncatsplit[(int)cut[currnode]-1];
        vals = catsplit[(int)cut[currnode]-1];
        for (v = 0; v < numvals; v++) {
    if (currval == vals[v]) {
      nextnode = left_child[currnode];
      break;
    }
        }
        if (nextnode == -1) {
    nextnode = right_child[currnode];
        }
      }

      currnode = nextnode-1;
      /* printf("curr node: %d \n", currnode);*/
    }
          
    *node_id = currnode+1;

}

/**
 * plhs = {var, cut, left_child, right_child, catsplit(cell array), attributes(numatt, numdata)}
 *
 */   
void mexFunction(int nlhs, mxArray *plhs[],
     int nrhs, const mxArray *prhs[])
{

    if (nrhs != 6) {
      printf("Error: wrong number of input arguments: %d.\n", nlhs);
      printf("Syntax: node_ids = treevalc(var, cut, left_child, right_child, catsplit, attributes)\n");
    }

    int* var = (int*)mxGetData(prhs[0]);
  /*   int* var = (int*)mxGetPr(prhs[0]); */
    double* cut = mxGetPr(prhs[1]);
    int* left_child = (int*)mxGetData(prhs[2]);
  /*   int* left_child = (int*)mxGetPr(prhs[2]); */
    int* right_child = (int*)mxGetData(prhs[3]);
  /*   int* right_child = (int*)mxGetPr(prhs[3]); */
    /* get catsplit variables */
    int nsplits = mxGetNumberOfElements(prhs[4]);
    int* ncatsplit = malloc(sizeof(int) * nsplits);
    double** catsplit = malloc(sizeof(double*) * nsplits);

    int n = 0;
    for (n = 0; n < nsplits; n++) {
      mxArray* catsplit_cell_mx = mxGetCell(prhs[4], n);
      if (catsplit_cell_mx == 0) {
        printf("null cell");
      }
      ncatsplit[n] = mxGetNumberOfElements(catsplit_cell_mx);
      catsplit[n] = (double*)mxGetPr(catsplit_cell_mx);
    }

    int numatt = mxGetM(prhs[5]);
    int numdata = mxGetN(prhs[5]);

    /*  printf("num data = %d   num att = %d\n", numdata, numatt);*/

    double* all_attributes = mxGetPr(prhs[5]);

    plhs[0] = mxCreateDoubleMatrix(numdata, 1, mxREAL);
    double* node_ids = mxGetPr(plhs[0]);

    int tmp_id;
    for (n = 0; n < numdata; n++) {
      treevalc(var, cut, left_child, right_child, ncatsplit, catsplit,
         &all_attributes[numatt*n], &tmp_id);
      node_ids[n] = (double)(tmp_id);
      /*    printf("final node id: %d\n", tmp_id); */
    }

    free(catsplit);
    free(ncatsplit);

}

[SHOBA MOHAN]

@ Walter Please refer the attached file and provide your valuable input.

Answer 1

[Walter Roberson]

Near line 87 you have executable code before you declare some of your local variables. That is valid C++, and it is valid in later C releases, but it is not valid in the default compilation model of C89.

You will need to do one of the following:

• move those lines to after the initialization; or
• put a {} around that initialization and to the rest of the function, so that the initializations are the first thing within a block; or
• add the -std=c99 compile option; or
• if you are using the GUI to set up the compile, find the place in the GUI to mark that you want C99 or C11.

[SHOBA MOHAN]

Thanks Walter. I tried with first two option got the following error

Undefined function 'treevalc' for input arguments of type 'cell'.

Which part shall i include -std=c99 compile option? I am not using GUI.