Getting Started with TRANSACT (32247-90007)

50 Chapter2

Using Character Mode I/O

Looping Structures

In most of the examples, we have used LEVEL as the way to get a program to loop.

Transact also has the verbs REPEAT, UNTIL, and WHILE to control looping.

For example, we could have written the last program using REPEAT as follows:

Figure 2-16. Program Using REPEAT to Loop

7 The DO verb designates the start of a block of code that is to be executed

under the control of the current verb, in this case the REPEAT verb. The

block of code is terminated with a DOEND verb. This is line 16 in the

example. Thus lines 8 through 15 are executed under the control of the

REPEAT statement.

DO/DOEND can also be used with the WHILE and IF verbs.

Replacing REPEAT with WHILE, the program looks like: WHILE statement”

1 system ex16,base=orders(";");

2 list(auto) customer;

3 data cust-no ("enter cust-no to delete");

4 if (cust-no) <> 0

5 then

6 repeat

7 do

8 set(key) list (cust-no);

9 get customer;

10 display;

11 input "delete this customer?";

12 if input = "Y","YES"

13 then delete(current) customer

14 else display "customer not deleted";

15 data cust-no ("enter cust-no to delete");

16 doend

17 until (cust-no) = 0;