sort( r, lo, up )
     ArrayToSort r;
     int lo, up;

     {int i, j;
     ArrayEntry tempr;
     while ( up>lo ) {
          i = lo;
          j = up;
          tempr = r[lo];
          /*** Split file in two ***/
          while ( i<j ) {
               for ( ; r[j].k > tempr.k; j-- );
               for ( r[i]=r[j]; i<j && r[i].k<=tempr.k; i++ );
               r[j] = r[i];
               }
          r[i] = tempr;
          /*** Sort recursively, the smallest first ***/
          if ( i-lo < up-i ) { sort(r,lo,i-1);  lo = i+1; }
               else    { sort(r,i+1,up);  up = i-1; }
          }
     }