Mine

#include <stdlib.h>
#include <stdio.h>

int     my_getnbr(char *str);
int     my_put_nbr(char *str);
int     my_putstr(char *str);
int     my_putchar(char c);

/*int   from2dec(int *nb, char *from)
{

}*/

char    *dec2to(int nb, int to)
{
  int   i;
  static  char  *rest;

  i = 0;
  rest = malloc(sizeof(nb) * sizeof(to));
  while (nb / to)
    {
      rest[i] = (nb % to);
      nb /= to;
      i++;
    }
  rest[i] = '\0';
  return (*rest);
}

int     main()
{
  my_putstr(dec2to(20, 2));
  return (0);
}