10 for i = 1 to 10
20 if rnd(0) > 0.5 then 110
30 goto 80
40 rem here's a stray NEXT that doesn't belong to any loop
50 next
60 print "finished the wrong next!"
70 goto 130
80 next
90 print "first next finished"
100 goto 130
110 next
120 print "second next finished"
130 rem rest of the program

> list
   10 input q
   20 if q > 10
   30   print q
   40   if q > 20
   50     print "big"
   60     endif
   70   print "small"
   80   endif
   90 print "done"
  100 end
> run
? 3
endif at line 60
small
done
> run
? 15
15
endif at line 60
small
done
> run
? 25
25
big
small
done
>

> list
   10 input q
   20 if q > 10
   30   print q
   40   if q > 20
   50     print "big"
   60     endif
   70   endif
   80 print "small"
  100 end
> run
? 5
endif at line 70
small
> run
? 15
15
endif at line 60
small
> run
? 25
25
big
small
>

         do
         {
            printf ("for loop: line %d\n", *(uint16_t *)where);
            where = execute(where);
            printf ("where = %p\n", where);
         }
         while (NULL != where);

> 10 for p = 1 to 3
> 20 print "hello "; p
> 30 next
> run
hello 1
hello 2
hello 3
> 10 for p = 3 to 3
> run
hello 3
> 10 for p = 4 to 3
> run
>

> list
   10 a = 0
   30 do
   35   b = 0
   40   do
   50     print a * 10 + b;
   60     b = b + 1
   70     while b < 10
   75   print
   80   a = a + 1
   90   while a < 10
  100 print "done"
> run
0 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19
20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39
40 41 42 43 44 45 46 47 48 49
50 51 52 53 54 55 56 57 58 59
60 61 62 63 64 65 66 67 68 69
70 71 72 73 74 75 76 77 78 79
80 81 82 83 84 85 86 87 88 89
90 91 92 93 94 95 96 97 98 99
done
>

char * do_do (char * where)
{
   /* Execute the 'do' clause by calling it recursively; it continues
    * until the matching 'while' statement. That statement returns NULL
    * if its comparison clause is true, indicating that the loop should
    * continue, or the address of the line following 'while'
    */
   
   char * loop_address;   // first line in the do loop
   char * cont_address;   // first line after the while
   char * while_address;   // the while line number
   
   where -= 4;
   //printf ("do at line %d\n", get_line(where));
   where = find_next_line (where);
   loop_address = where;
   while_address = find_pair (where, DO);
   cont_address = find_next_line (while_address);   // first line after while
   //printf ("cont = %d, loop = %d\n",
   //   get_line(cont_address), get_line(loop_address));
   do
   {
      where = loop_address;
      do
      {
         // when we execute the while, we are returned a NULL if the
         // condition is true
         //printf("do: executing line %d\n", get_line(where));
         where = execute(where);
         if (NULL != where)
         {
            //printf("in do: next line %d\n", get_line(where));
            if (get_line(where) == get_line(cont_address))
            {
               //printf ("break\n");
               break;
            }
         }
         else
         {
            //printf ("inner done, pointing to %d\n", get_line(where));
         }
      }   
      while (NULL != where);
   }
   while (NULL == where);
   //while (get_line(where) < get_line(while_address));
   return where;
}

uint8_t * do_while (uint8_t * where)
{
   /* test a condition; if true, return the value zero
    * otherwise, return the address of the next line
    */
    if (compare())
    {
       //printf ("while is true\n");
       return NULL;
    }
    else
    {
       //printf ("while is false\n");
       return find_next_line (where - 4);
    }
   return where;
}