' PRINT "Hello" 100 times
'
LET COUNT = 1
DO WHILE COUNT <= 100  
  PRINT "Hello"  
  LET COUNT = COUNT + 1
LOOP
'
END

Ending Value in a Variable

Here is a small but important change to the program:

' PRINT "Hello" 10 times
'
LET ENDVALUE = 10
LET COUNT = 1
DO WHILE COUNT <= ENDVALUE
  PRINT "Hello"  
  LET COUNT = COUNT + 1
LOOP
'
END

The first statement saves the value 10 in the variable ENDVALUE. This statement is executed only once, since it is not part of the loop. Then the DO WHILE statement compares the number in COUNT to the number in ENDVALUE:

DO WHILE COUNT <= ENDVALUE 

Since there is a 10 in ENDVALUE, this is the same as:

DO WHILE COUNT <= 10

The very first time this is done, COUNT has a 1 in it, so this is the same as:

DO WHILE  1 <= 10

So the loop body executes. Then COUNT is changed to 2, and the DO WHILE test is performed again:

DO WHILE COUNT <= ENDVALUE 
           ^        ^
           |        |
           |        +---- holds a 10
           |
           +----- holds a 2 (this time around)

And so on. The loop will work just like it did before, but now the 10 is kept inside ENDVALUE rather put explicitly in the DO WHILE test. The advantage is that the number in ENDVALUE can be changed, and then the loop will execute a different number of times.

' Mystery Program
'
LET ENDVALUE = 5
LET COUNT = 1
DO WHILE COUNT <= ENDVALUE
  PRINT "Hello"  
  LET COUNT = COUNT + 1
LOOP
'
END