void insert( key, r )
     typekey key;  dataarray r;

     { extern int n, nextfree;
       int i;

     i = hashfunction( key );
     if ( empty(r[i]) ) {
          r[i].k = key;
          r[i].next = (-1);
          n++;
          }
     else { /*** Find end of chain ***/
          while ( r[i].next!=(-1) && r[i].k!=key )  i = r[i].next;
          if ( r[i].k==key )  Error /*** key already in table ***/;
          else {
               /*** Find next free location ***/
               while ( !empty(r[nextfree]) && nextfree>=0 )  nextfree--;
               if ( nextfree<0 )  Error /*** Table is full ***/;
               else {
                    r[i].next = nextfree;
                    r[nextfree].k = key;
                    r[nextfree].next = (-1);
                    n++;
                    }
               }
          }
     }