Code to add x minutes to time in fillin field - openedge

Question

I'm a beginner to programming and to Progress, first post on StackOverflow, hope I'm posting in the right place!
I have a fillin field where I enter a time (hh:mm), character format. I also have two arrows, one pointing forward and one backward, and I want them to add / subtract 20 min respectively when pushed.
What would be a good way to write code for this? Turn the current time value to integer and seconds past midnight and then add /subtract 1200 sec? How would I get the result back to a hh:mm format to display in the fillin?
Any help greatly appreciated!
/Ellen

Answer 1

I think this will do what you need. Have the ON CHOOSE triggers on your arrow buttons run the changeMins procedure. Pass in the character time string from your fill-in and either "Add" or "Subtract". The output value will be the new adjusted time string. You can then set the screen value of your fill-in to that output value.
DEFINE VARIABLE cTime AS CHARACTER NO-UNDO.
cTime = "12:45".
RUN changeMins (INPUT-OUTPUT cTime, INPUT "Add").
MESSAGE cTime VIEW-AS ALERT-BOX INFORMATION BUTTONS OK.
PROCEDURE changeMins:
DEFINE INPUT-OUTPUT PARAMETER pcTime AS CHARACTER NO-UNDO.
DEFINE INPUT PARAMETER pcAction AS CHARACTER NO-UNDO.
DEFINE VARIABLE iHr AS INTEGER NO-UNDO.
DEFINE VARIABLE iMn AS INTEGER NO-UNDO.
/* Split the time string into hours and minutes */
ASSIGN
iHr = INTEGER(ENTRY(1, pcTime, ":"))
iMn = INTEGER(ENTRY(2, pcTime, ":"))
NO-ERROR.
IF ERROR-STATUS:ERROR THEN RETURN.
/* Adjust the time */
CASE pcAction:
WHEN "Add" THEN iMn = iMn + 20.
WHEN "Subtract" THEN iMn = iMn - 20.
END CASE.
/* Correct for boundaries */
IF iMn > 59 THEN
ASSIGN
iMn = iMn - 60
iHr = iHr + 1.
IF iMn < 0 THEN
ASSIGN
iMn = iMn + 60
iHr = iHr - 1.
IF iHr > 23 THEN iHr = iHr - 24.
IF iHr < 0 THEN iHr = iHr + 24.
/* Build the new time string */
pcTime = STRING(iHr, "99") + ":" + STRING(iMn, "99").
END PROCEDURE.
In this example, change the cTime string to different times and run it.

Answer 2

The Progress TIME function returns the integer number of seconds past midnight. So your idea of converting to such an integer is consistent with other uses within the 4gl which is a positive.
Personally I would keep the UI and the internal storage independent. So I would probably have a variable for the hour, another for the minute and a 3rd for seconds (if you need that). And I would use integers, rather than characters, for all 3.
I've no idea what version of Progress or what the environment that you are running in is but this quick and dirty little snippet might have some useful tidbits:
define variable hh as integer no-undo format ">9".
define variable mm as integer no-undo format "99".
define variable ss as integer no-undo format "99".
define variable myTime as integer no-undo.
form
hh mm ss
with
frame a
.
on value-changed of hh in frame a do:
if integer( self:screen-value ) > 23 then
do:
hh = 23.
display hh with frame a.
end.
end.
on value-changed of mm in frame a do:
if integer( self:screen-value ) > 59 then
do:
mm = 59.
display mm with frame a.
end.
end.
on value-changed of ss in frame a do:
if integer( self:screen-value ) > 59 then
do:
ss = 59.
display ss with frame a.
end.
end.
update hh mm ss with frame a.
myTime = (( hh * 3600 ) + ( mm * 60 ) + ss ).
display string( myTime, "hh:mm:ss am" ).

Answer 3

Deriving from TheDrooper's Code I would probably write something like the following code to fully utilize the built-in functions.
Shorter code that is still at least as easy to understand is often preferable.
Also consider that Progress does not have an optimizing compiler. If you can replace replace several simple statements with less statements (even if those are more complex and powerful than needed) the code is not only more maintainable but also faster.
DEFINE VARIABLE cTime AS CHARACTER NO-UNDO.
cTime = "12:45".
RUN changeMins (INPUT-OUTPUT cTime, INPUT "Add").
MESSAGE cTime VIEW-AS ALERT-BOX INFORMATION BUTTONS OK.
PROCEDURE changeMins:
DEFINE INPUT-OUTPUT PARAMETER pcTime AS CHARACTER NO-UNDO.
DEFINE INPUT PARAMETER pcAction AS CHARACTER NO-UNDO.
DEFINE VARIABLE iMn AS INTEGER NO-UNDO.
iMn = INTEGER(ENTRY(1, pcTime, ":")) * 60
+ INTEGER(ENTRY(2, pcTime, ":"))
NO-ERROR. /* Calculate minutes since midnight */
IF ERROR-STATUS:ERROR THEN RETURN.
/* Adjust the time */
CASE pcAction:
WHEN "Add" THEN iMn = iMn + 20.
WHEN "Subtract" THEN iMn = iMn - 20.
END CASE.
/* Build the new time string */
pcTime = string(iMn * 60, 'HH:MM'). /* Convert minutes to seconds and convert the result to a string */
END PROCEDURE.
If you need to allow for higher hour values (eg. if the field doesn't represent a time of day but a time interval) you can't just convert the resulting integer with the string function. In that case you could write
pcTime = string(iMn / 60, '99') + ':' + string(iMn mod 60, '99').
(Both TheDrooper and Tom Bascom seem to assume time of day.)