Do...Loop
Statement
Do [While | Until ''condition''] [''statements''] [EXIT Do] [''statements''] Loop or Do [''statements''] [EXIT Do] [''statements''] Loop [While | Until ''condition'']
Description
Do...Loop repeats a block of statements While a given condition is TRUE, or UNTIL a given condition becomes TRUE. The required component, condition, is any expression that can be evaluated as TRUE or FALSE. The optional component, statements, are the statements executed during the body of the loop. Any number of optional EXIT Do statements can be used to exit a loop before it is finished. Do...Loop statements can be nested, and any EXIT DO statements in a nested loop transfer execution to one level above the loop where the EXIT Do occurs.
Placing the While/Until clause directly after Do causes condition to be evaluated before the first loop is executed, if condition is FALSE statements are never executed; placing the While/Until clause after LOOP causes the body of the loop to be executed before condition is evaluated, statements will always be executed, at least once.
Example
REM Do...Loop Example
'Do...Loop repeats a block of statements
Dim Counter
Counter = 1
'Loop that prints 1 to 5
Do While Counter < 6
PRINT "Do While...Loop:", Counter
Counter = Counter + 1
Loop
PRINT
'Infinite loop that uses EXIT DO toterminate
Counter = 1000
Do
PRINT "Infinite Loop:", Counter
IF Counter >= 1000000 THEN
EXIT DO
Counter = Counter * 10
Loop
Output
Do While...Loop: 1 Do While...Loop: 2 Do While...Loop: 3 Do While...Loop: 4 Do While...Loop: 5 Infinite Loop: 1000 Infinite Loop: 10000 Infinite Loop: 100000 Infinite Loop: 1000000