CONCAT

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

/** concatenate strings without limit  */

#define max_concat 256

/* concatenate */
#define CONCAT(...)   ( __extension__ ({                        \
  char* sarray[] = { __VA_ARGS__ , NULL };                      \
  char* out =  calloc(max_concat, sizeof(char));                \
  do { size_t n = 0;                                            \
  while (sarray[n] != NULL)                                     \
    { sprintf( out, "%s%s", out, sarray[n] ); n++; }            \
  }while(0);                                                    \
  out = realloc(out, strlen(out)+1);                            \
}))



int main( int argc, char** argv, char** env)
{
  char* str = CONCAT( "dog", "cat", "horse", "butt", "smacker", " - ", "SNAP", "!" );
  fprintf(stdout, "%s\n" , str);
  free (str);
  return 0;
}

/** NOTES
*   the ( __extension__({  and  subsequent  }))
*   enclose the macro as a gnu extension so that
*   it is not flagged as a warning in pedantic mode.
*   It also creates a scope where statically allocated
*   variables can be created and disposed of at the "return".
*
*  The last statement is what the macro "returns", in this case
*  the dynamically allocated string (out). The realloc command
*  is not really needed but right-sizes the string. It still must
*  be freed later.
*/