#include <stdio.h>
#include <strings.h>


void gen(char *head, char *a, int k)
{
   char myHead[10];
   char *c, *e;

   if ( k == 0 )
   {
      printf(">> %s\n", head);
      return;
   }

   strcpy(myHead, head);
   for ( e = myHead; *e != '\0'; e++ );

   *(e+1) = '\0';

   for ( c = a; *c != '\0'; c++ )
   {
      *e = *c;

      gen(myHead, c+1, k-1);
   }
}


int main(int argc, char **argv)
{
   char a[] = "abcde";
   char head[] = "";
   int k = 3;

   gen(head, a, k); 
}