FOR-LOOP

While the number of iterations through a WHILE loop is unknown till the loop completes, then the number of iterations through a FOR loop is known before the loop is entered. The FOR loops iterate over a particular range of integers. The range is the part of an iteration scheme that is enclosed by the keywords FOR and LOOPS. A double dot (..) serve as the range operator. The syntax is as shown below:

FOR counter IN [REVERSE] lower_bound..higher_bound LOOP
sequence_of_statements
END LOOP;


The range is computed when the FOR loop is first entered and is never re-evaluated.



As the next illustration shows, the series of statements is executed once for each integer in the range. After each of the iteration, the loop counter is incremented.

FOR i IN 1..3 LOOP -- assign the values 1,2,3 to i
sequence_of_statements -- executes three times
END LOOP;


The following illustration shows that if the lower bound equals the higher bound, the series of the statements is executed once:

FOR i IN 3..3 LOOP -- assign the value 3 to i
sequence_of_statements -- executes one time
END LOOP;