c++ problem with the following code can't display the odds num

#include<stdio.h>
// main function
int main(void){
  // declare strings
  int nums[11] = {1,2,3,4,5,6,7,8,9,10,11};
  char odds[20], evens[20];
  


  // setup indexes to track current index of  arrays. 
  int odd_index, even_index, num_index, remainder, i;
  char curr_num;
  num_index=0;
  odd_index=0;
  even_index=0;
  remainder=0;
  
  for(i = 1; i < 10; i++){
      curr_num = nums[i];
      remainder = curr_num %2;
      if (remainder == 0) {
          evens[even_index] = curr_num;
          even_index++;
      }else{
          odds[odd_index] = curr_num;
          odd_index++;
      }
  }
printf("%s is the odd nums \n", odds);
  return 0;
}

Answer 1

[Walter Roberson]

To be able to display output in a C function called from MATLAB, you need to use https://www.mathworks.com/help/matlab/apiref/mexprintf.html mexPrintf() instead of printf()

You will also need to build the interface properly in order to call the code from MATLAB; see https://www.mathworks.com/help/matlab/call-mex-files-1.html

Also, since you are building a character vector, you should be careful to store printable characters in it. You are storing the binary value of the integers such as 3 into the odds array, where it will become char(3) rather than '3' . And remember your numbers go up to 11, so if you want printable characters you need two characters for 10 and 11. And remember a seperator between the characters.

[James Tursa]

And the strings are not null-terminated, so the printf can run off the end of the array into invalid memory.