Release 10.1A: OpenEdge Development:
Progress 4GL Reference

&IF, &THEN, &ELSEIF, &ELSE, and &ENDIF preprocessor directives

These directives set logical conditions for the inclusion of blocks of code to compile.

Syntax

&IF expression &THEN block [ &ELSEIF expression &THEN block ] ... [ ELSE block ] &ENDIF

expression

An expression that can contain preprocessor name references, the operators listed in
Table 6, the Progress functions listed in Table 7, and the DEFINED( ) preprocessor function.

When it encounters an &IF directive, the preprocessor evaluates the expression that immediately follows. This expression can continue for more than one line; the &THEN directive indicates the end of the expression. If the expression evaluates to TRUE, then the block of code between it and the next &ELSEIF, &ELSE, or &ENDIF is compiled. If the expression evaluates to FALSE, the block of code is not compiled and the preprocessor proceeds to the next &ELSEIF, &ELSE, or &ENDIF directive. No include files referenced in this block of code are included in the final source. You can nest &IF directives.

The expression that follows the &ELSEIF directive is evaluated only if the &IF expression tests false. If the &ELSEIF expression tests TRUE, the block of code between it and the next &ELSEIF, &ELSE, or &ENDIF directive is compiled. If the &ELSEIF expression tests FALSE, the preprocessor proceeds to the next &ELSEIF, &ELSE, or &ENDIF directive.

The block of code between the &ELSE and &ENDIF directives is compiled only if the &IF expression and the &ELSEIF expressions all test false. If there are no &ELSEIF directives, the block of code is compiled if the &IF expression tests false.

Once any &IF or &ELSEIF expression evaluates to TRUE, no other block of code within the &IF...&ENDIF block is compiled.

The &ENDIF directive indicates the end of the conditional tests and the end of the final block of code to compile.

Table 5 shows how preprocessor expressions are evaluated.

Table 5: Preprocessor expressions 

Type of expression	TRUE	FALSE
LOGICAL	TRUE	FALSE
CHARACTER	non-empty	empty
INTEGER	non-zero	0
DECIMAL	not supported	not supported

Table 6 lists the operators supported within preprocessor expressions. These operators have the same precedence as the regular Progress 4GL operators.

Table 6: Preprocessor operators 

Operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division
=	Equality
<>	Inequality
>	Greater than
<	Less than
=>	Greater than or equal to
<=	Less than or equal to
AND	Logical and
OR	Logical or
NOT	Logical not
BEGINS	Compares the beginning letters of two expressions
MATCHES	Compares two strings

Table 7 lists the Progress 4GL functions supported within preprocessor expressions.

Table 7: Functions allowed in preprocessor expressions 

ABSOLUTE	ASC	AUDIT-ENABLED
DATE	DAY	DBTYPE
DECIMAL	ENCODE	ENTRY
ETIME	EXP	FILL
INDEX	INTEGER	KEYWORD
KEYWORDALL	LC	LEFT-TRIM
LENGTH	LIBRARY	LOG
LOOKUP	MATCHES	MAXIMUM
MEMBER	MINIMUM	MODULO
MONTH	NUM-ENTRIES	OPSYS
PROPATH	PROVERSION	RANDOM
REPLACE	RIGHT-TRIM	R-INDEX
ROUND	SQRT	STRING
SUBSTITUTE	SUBSTRING	TIME
TODAY	TRIM	TRUNCATE
WEEKDAY	YEAR

Note

When the preprocessor evaluates expressions, all arithmetic operations are performed with 32-bit integers. Preprocessor name references used in arithmetic operations must evaluate to integers.

See also

&GLOBAL-DEFINE preprocessor directive, &SCOPED-DEFINE preprocessor directive, &UNDEFINE preprocessor directive