Possible syntax are:

 

 
DO WHILE expr statements LOOP
DO UNTIL expr statements LOOP
DO statements LOOP WHILE expr DO statement LOOP UNTIL expr
 

 

Statements will be executed WHILE expr is true, or UNTIL expr is true. if expr is before statements, then the control condition will be tested before iteration. Otherwise, control condition will be tested after iteration. Examples:

DO
   K = I mod J
I = J
J = K
LOOP UNTIL J = 0
 
DO
I = I mod J
I = J
J = K
LOOP WHILE J <> 0
 
DO WHILE I < 0
 …
LOOP
 

 

 

for statements