DO Loops
Another method of looping is the DO … LOOP structure which looks like this:
DO WHILE condition
<statement>
<statement>
LOOP
This will start by testing the condition and if it is true the statements will be executed until the LOOP
command is reached, at which point the program will return to DO statement and the condition will be
tested again, and if it is still true the loop will execute again. The condition is the same as in the IF
command (ie, X < Y).
For example, the following will keep printing the word "Hello" on the console for 4 seconds then stop:
Timer = 0
DO WHILE Timer < 4000
PRINT "Hello"
LOOP
Note that Timer is a function within MMBasic which will return the time in milliseconds since the timer was reset. A reset is done by assigning zero to Timer (as done above) or when powering up the PicoMite.
A variation on the DO … LOOP structure is the following:
DO
<statement>
<statement>
LOOP UNTIL condition
In this arrangement the loop is first executed once, the condition is then tested and if the condition is
false, the loop will be repeatedly executed until the condition becomes true. Note that the test in
LOOP UNTIL is the inverse of DO WHILE.
For example, similar to the previous example, the following will also print "Hello" for four seconds:
Timer = 0
DO
PRINT "Hello"
LOOP UNTIL Timer >= 4000
Both forms of the DO … LOOP essentially do the same thing, so you can use whatever structure fits
with the logic that you wish to implement.
Finally, it is possible to have a DO Loop that has no conditions at all.
DO
<statement>
<statement>
LOOP
This construct will continue looping forever and you, as the programmer, will need to provide a way
to explicitly exit the loop (the EXIT DO command will do this).
For example:
Timer = 0
DO
PRINT "Hello"
IF Timer >= 4000 THEN EXIT DO
LOOP