7.8.3 CASE Examples
Using the CASE command with OR operations
Using the CASE command with operations other than "=" (equal to)
Using the CASE command with compound expressions
This example illustrates the most basic type of CASE command processing.
Imagine that a user inputs a value into field #DEPTMENT and that a CASE command to be used to implement this logic:
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Structurally, a CASE command to implement this logic would look like this:
CASE OF_FIELD(#DEPTMENT)
WHEN VALUE_IS('= ADM')
<< Logic >>
WHEN VALUE_IS('= AUD')
<< Logic >>
WHEN VALUE_IS('= FLT')
<< Logic >>
WHEN VALUE_IS('= TRVL')
<< Logic >>
OTHERWISE
<< Logic >>
ENDCASE
A sample program to fully implement this logic might be coded like this:
BEGIN_LOOP
REQUEST FIELDS(#DEPTMENT (#SECTION *OUTPUT))
CASE OF_FIELD(#DEPTMENT)
WHEN VALUE_IS('= ADM')
CHANGE FIELD(#SECTION) TO(A)
MESSAGE MSGTXT('ADM was entered')
WHEN VALUE_IS('= AUD')
CHANGE FIELD(#SECTION) TO(B)
MESSAGE MSGTXT('AUD was entered')
WHEN VALUE_IS('= FLT')
CHANGE FIELD(#SECTION) TO(C)
MESSAGE MSGTXT('FLT was entered')
WHEN VALUE_IS('= TRVL')
CHANGE FIELD(#SECTION) TO(D)
MESSAGE MSGTXT('TRVL was entered')
OTHERWISE
CHANGE FIELD(#SECTION) TO(E)
MESSAGE MSGTXT('Other value was entered')
ENDCASE
END_LOOP
Imagine you have to implement this logic:
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If you code nested IF-ELSE-END blocks you will end up with logic like this:
IF COND('(#DEPTMENT = ADM) or (#DEPTMENT = FLT) or (#DEPTMENT = TRVL)')
CHANGE FIELD(#SECTION) TO(A)
MESSAGE MSGTXT('Either ADM , FLT or TRVL was entered')
ELSE
IF COND('(#DEPTMENT = AUD) or (#DEPTMENT = INF) or (#DEPTMENT = MKT)')
CHANGE FIELD(#SECTION) TO(B)
MESSAGE MSGTXT('Either AUD, INF or MKT was entered')
ELSE
CHANGE FIELD(#SECTION) TO(C)
MESSAGE MSGTXT('Other value was entered')
ENDIF
ENDIF
However, by using a CASE command you can code this instead:
CASE OF_FIELD(#DEPTMENT)
WHEN VALUE_IS('= ADM' '= FLT' '= TRVL')
CHANGE FIELD(#SECTION) TO(A)
MESSAGE MSGTXT('Either ADM, FLT or TRVL was entered')
WHEN VALUE_IS('= AUD' '= INF' '= MKT')
CHANGE FIELD(#SECTION) TO(B)
MESSAGE MSGTXT('Either AUD, INF or MKT was entered')
OTHERWISE
CHANGE FIELD(#SECTION) TO(C)
MESSAGE MSGTXT('Other value was entered')
ENDCASE
Using the CASE command with OR operations
Imagine that when field #TEST contains A or B or C you have to perform some operation.
If it contains X or Y or Z you have to perform some other operation.
If it contains any other value it all then you have to perform yet another operation.
You could use a CASE command structured like this to implement the required logic:
CASE OF_FIELD(#TEST)
WHEN VALUE_IS('= A' '= B' '= C')
<< Logic Block 1 >>
WHEN VALUE_IS('= X' '= Y' '= Z')
<< Logic Block 2>>
OTHERWISE
<< Logic Block 3>>
ENDCASE
Using the CASE command with operations other than "=" (equal to)
Imagine that when field #COPIES needs to be validated according to these rules:
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Hence a CASE command can be used like this:
DEFINE FIELD(#COPIES) TYPE(*DEC) LENGTH(3) DECIMALS(0) EDIT_CODE(N) DEFAULT(+1)
BEGIN_LOOP
REQUEST FIELDS(#COPIES)
CASE OF_FIELD(#COPIES)
WHEN VALUE_IS('= 0')
MESSAGE MSGTXT('Value of zero is invalid')
WHEN VALUE_IS('< 0')
MESSAGE MSGTXT('Value is negative')
WHEN VALUE_IS('<= 50')
MESSAGE MSGTXT('Value is sensible')
OTHERWISE
MESSAGE MSGTXT('Value is probably incorrect')
ENDCASE
END_LOOP
Using the CASE command with compound expressions
In a situation whereby a field #DISCOUNT needs to be validated by using a mathematical calculation such as this:
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This can be coded by using the CASE command:
DEFINE FIELD(#DISCOUNT) TYPE(*DEC) LENGTH(11) DECIMALS(2) EDIT_CODE(1)
DEFINE FIELD(#QUANTITY) TYPE(*DEC) LENGTH(3) DECIMALS(0)
BEGIN_LOOP
REQUEST FIELDS(#DISCOUNT #QUANTITY)
CASE OF_FIELD(#DISCOUNT)
WHEN VALUE_IS('> (#QUANTITY * 0.1)')
MESSAGE MSGTXT('Discount value is larger than quantity times 0.1')
WHEN VALUE_IS('< (#QUANTITY * 0.1)')
MESSAGE MSGTXT('Discount value is less than quantity times 0.1')
OTHERWISE
MESSAGE MSGTXT('A correct discount value was entered')
ENDCASE
END_LOOP