Program Flow.

In the format:
Line_number command

EXAMPLE 1 - NO LOOPS

Program:
10 print Hi
20 print J.

Output:
Hi
J.

Execution of program by line:
10
20

EXAMPLE 2 - GOTO

Program:
10 print Hi
20 print J.
30 GOTO 50
40 print This will not print.
50 print Goodbye!

Output:
Hi
J.
Goodbye!

Comment:
Goto skips around.

Execution of program by line:
10
20
30 goto skips to line 50 
50

EXAMPLE 3 - IF

Program:
10 a = 1
20 IF (a = 1) then
30    { print a is 1 }
40 IF (a = 2) then
50    { print a is 2 }
60 print bye!

Output:
a is 1
bye!

Execution of program by line:
10
20 this criteria is true, do what's in the {}'s
30
40 this criteria is not true, skip the stuff in the brackets
60

Comment:
The {}'s go with the if statement and mean to
run all code between them if the IF criteria is met. 

EXAMPLE 4 - CASE

Program:                              Equivalent Program:
10  a = 3                             10  a = 3
20  BEGIN CASE a {
30    CASE 1                          20  IF ( a = 1 )
40       { print a = 1 }              30      { print a = 1 }
50    CASE 2                          40  IF ( a = 2 )
60       { print a = 2 }              50      { print a = 2 }
70    CASE 3                          60  IF ( a = 3 )
80       { print a = 3 }              70      { print a = 3 }
90    CASE 4                          80  IF ( a = 4 )
100     { print a = 4 }               90      { print a = 4 }
110   CASE ELSE                       100 IF ( a <> 1,2,3,or 4)
120     { print a not 1234 }          110     { print a not 1234 }
130 } END CASE

Output:                               Output:
a = 3                                 a = 3

Comments:
Notice that the equivalent program doesn't need line 20 or 130.
Lines 30 to 120 are inside the CASE's {}'s so they all go together.

Execution of program by line:
10                                    10
20 variable to check is a             20  a is not 1, skip 30
30 a is not 1, skip 40                40  a is not 2, skip 50
50 a is not 2, skip 60                60  a is 3, do 70
70 a is 3, do 80                      70
80                                    80  a is not 4, skip 90
90 a is not 4, skip 100               100 a is not 1,2,3,or 4, skip 110
110 we matched a, so skip 120
130

EXAMPLE 5 - IF AND {}'S

Program:
10  a = 1
20  IF (a = 1)
30     {
40       print a is 1
50       print Woohoo!
60     }
70  IF (a = 2)
80     {
90       print a is 2
100      print it better not be 2
110    }
120 print Done!

Output:
a is 1
Woohoo!
Done!

Execution of program by line:
10
20 a is 1, so do lines 30-60 because they are in {}'s
30
40
50
60
70 a is not 2, so skip lines 80-110 because they are in {}'s
120

EXAMPLE 6 - FOR

Program:                          Equivalent Program:
10 print beginning                10 print beginning
20 FOR (a = 0, a < 5, a++)        20 a = 0
30    {                           30 print a = $a
40      print a = $a              40 print This happens too!
50      print This happens too!   50 if (a < 5)
60    }                           60    { goto 30 }
70 print ending                   70 print ending

Output:                           Output:
beginning                         beginning
a = 0                             a = 0
This happens too!                 This happens too!
a = 1                             a = 1
This happens too!                 This happens too!
a = 2                             a = 2
This happens too!                 This happens too!
a = 3                             a = 3
This happens too!                 This happens too!
a = 4                             a = 4
This happens too!                 This happens too!
ending                            ending

Comments:
a starts at 0, loops until it is no longer less than 5, adding 1
to a at each loop

Execution of program by line:
10
20 a starts at 0, a < 5, do lines 30-60 as they are in the for's {}'s
30
40
50
60 end of loop, add 1 to a, goto 20
20 a = 1 < 5, do lines 30-60
30
40
50
60 end of loop, add 1 to a, goto 20
20 a = 2 < 5, do lines 30-60
30
40
50
60 end of loop, add 1 to a, goto 20
20 a = 3 < 5, do lines 30-60
30
40
50
60 end of loop, add 1 to a, goto 20
20 a = 4 < 5, do lines 30-60
30
40
50
60 end of loop, add 1 to a, goto 20
20 a = 5, this is not less than 5, skip lines 30-60 due to {}'s
70

EXAMPLE 7 - WHILE

Program:
10 print beginning
20 a = 0
30 WHILE (a < 5)
40    { print a = $a
50      print This happens too!
60      a = a + 1 }
70 print ending

Output:
Same as example 6 above.

Execution of program by line:
10
20
30 a = 0, if a < 5, do lines 40-60 between the {}'s
40
50
60 end of loop } so goto 30
30 a = 1, if a < 5, do lines 40-60 between the {}'s
40
50
60 end of loop } so goto 30
30 a = 2, if a < 5, do lines 40-60 between the {}'s
40
50
60 end of loop } so goto 30
30 a = 3, if a < 5, do lines 40-60 between the {}'s
40
50
60 end of loop } so goto 30
30 a = 4, if a < 5, do lines 40-60 between the {}'s
40
50
60 end of loop } so goto 30
30 a = 5, a is not < 5, skip lines 40-60 between the {}'s
70

EXAMPLE 8 - NESTED {}'s

Program:
10  print beginning
20  for (a = 0, a < 3, a++ )
30      {
40       print inside for loop
50       if ( a = 1 )
60          {
70           print a = 1
80           print Woohoo!
90          }
100      print still inside loop
110      }
120 print ending

Output:
beginning
inside for loop
still inside loop
inside for loop
a = 1
Woohoo!
still inside loop
inside for loop
still inside loop
ending

Comment:
Nested {}'s and ()'s all work from the inside-most ones outward.

Execution of program by line:
10
20  a = 0, keep going while a < 3, add 1 at end, do lines 30-110
30
40
50  a <> 1, skip lines 60-90
100
110 increment a, goto 20
20  a = 1, keep going, do lines 30-110
30
40
50  a = 1, so do lines 60-90
60
70
80
90
100
110 increment a, goto 20
20  a = 2, which is still < 3, so do lines 30-110
30
40
50  a <> 1, skip lines 60-90
100
110 increment a, goto 20
20  a = 3, a is not < 3, so skip lines 30-110
120