/* demo.src/qsort.c; cpl4.10 */

void swap(void* v[], int i, int j);
char Switch(void* first, void* second);


/* qqsort: sort v[left],...,v[right] into increasing order */
void qqsort(void* v[], int left, int right)
{
    int i, last;
    if (left >= right)
        return;
    swap(v, left, (left + right)/2);  /* move partition element */
    last = left;
    for (i = left+1; i <= right; i++) {/* partition */
        if (Switch(v[i],v[left]))
            swap(v, ++last, i);
	}

    swap(v, left, last);    /* restore partition element */
    qqsort(v, left, last-1);
    qqsort(v, last+1, right);
}

char Switch(void* first, void* second){
/* return true 0 if first and second need to be switched
otherwise return non-zero  
If the first line is contained in the second we don't switch -
if the second line is contained in the first we do. 
*/
	char	*ff, *tt;
ff=(char*)first;tt=(char*)second;
for(; *ff!=0 && *tt!=0; ff++, tt++) {
  if( (*ff)<(*tt) ) return 1;
  else if( (*ff) > (*tt) ) return 0;
  }
if( *ff==0 ) return 1; else return 0;
	
}

/* swap: interchange v[i] and v[j] */
void swap(void* v[], int i, int j)
{
    void* temp;

    temp = v[i];
    v[i] = v[j];
    v[j] = temp;
}