| Navigation: Language Reference > 12 - Execution Control > Control Structures >====== IF (conditional execution structure) ====== |    |
IF logical expression [ THEN ]
statements
[ ELSIF logical expression [ THEN ]
statements ]
[ ELSE
statements ]
END
| IF | Initiates a conditional statement execution structure. |
| logical expression | A variable, procedure, or expression which evaluates a condition. Control is determined by the result (true or false) of the expression. Zero (or blank) evaluates as false, anything else is true. |
| THEN | The statements following THEN execute when the preceding logical expression is true. If used, THEN must only appear on the same line as IF or ELSIF. |
| statements | An executable statement, or a sequence of executable statements. |
| ELSIF | The logical expression following an ELSIF is evaluated only when all preceding IF or ELSIF conditions were evaluated as false. |
| ELSE | The statements following ELSE execute only when all preceding IF and ELSIF options evaluate as false. ELSE is not required, however, when used, it must be the last option in the IF structure. |
An IF structure controls program execution based on the outcome of one or more logical expressions. IF structures may have any number of ELSIF statement groups. IF structures may be “nested” within other executable structures. Other executable structures may be nested within an IF structure. Each IF structure must terminate with an END statement (or period).
Example:
IF Cus:TransCount = 1 !If new customer
AcctSetup !call account setup procedure
ELSIF Cus:TransCount > 10 AND Cus:TransCount <; 100 !If regular customer
DO RegularAcct !process the account
ELSIF Cus:TransCount > 100 !If special customer
DO SpecialAcct !process the account
ELSE !Otherwise
DO NewAcct !process the account
IF Cus:Credit
CheckCredit
ELSE
CLEAR(Cus:CreditStat)
END
! verify credit status
END
IF ERRORCODE()
ErrHandler(Cus:AcctNumber,Trn:InvoiceNbr) !Handle errors
END
See Also: