generating permutations

Here's some code that I wrote to demonstrate a recursive algorithm for generating permutations of a vector. I deliberately wrote it in 'C', as I believe it is the lowest common denominator for computer science languages today.

The algorithm was listed in How to solve it: Modern Heuristics

typedef struct VEC_
{
 int *x;
 int sz;
} VEC;

// call: pos_perm(v,0,-1);
int pos_perm(VEC *v,int pos,int k)
{
 k = k + 1;
 v->x[pos] = k;
 //printf("--pos=%d k=%d ",pos,k);
 if ( k == v->sz )
 {
  print(v);
 }
 for (int q=0;q<v->sz;q++)
 {
  if ( v->x[q] == 0 ) pos_perm(v,q,k);
 }
 k = k - 1;
 v->x[pos] = 0;
 //printf("pos=%d k=%d\n",pos,k);
}