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unary-operator ( term term binary-operator term )
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A literal (constant) value represented according to its data type (Data types)
A reference to a variable scoped to the current procedure, user-defined function, or method of a class, or to an accessible class-based variable data member, including a subscripted or unsubscripted array reference (DEFINE VARIABLE statement, Class-based data member access)
A reference to a parameter (of any mode) defined for the current procedure, user-defined function, or method of a class, including a subscripted or unsubscripted array reference (DEFINE PARAMETER statement)
A reference to a readable class-based property or COM property, including a subscripted or unsubscripted array reference (DEFINE PROPERTY statement, Class-based property access, Accessing COM object properties and methods)
Readable handle attribute reference (Accessing handle attributes and methods)
Readable system handle reference (Handle Reference)
An ABL built-in or user-defined function call (FUNCTION statement)
A handle method, non-VOID COM method, or non-VOID class-based method call (Accessing handle attributes and methods, Accessing COM object properties and methods, Class-based method call)
An Expression (recursive)
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DEFINE VARIABLE iDim1 AS INTEGER NO-UNDO.
DEFINE VARIABLE iDim2 AS INTEGER NO-UNDO. DEFINE VARIABLE iDim1Extent AS INTEGER NO-UNDO INITIAL 3. DEFINE VARIABLE iDim2Extent AS INTEGER NO-UNDO INITIAL 5. DEFINE VARIABLE iArray AS CHARACTER NO-UNDO EXTENT 15 INITIAL ["A","B","C","D","E", /* iDim1 = 1 */ "F","G","H","I","J", /* iDim1 = 2 */ "K","L","M","N","O"]. /* iDim1 = 3 */ DO iDim1 = 1 TO iDim1Extent: DO iDim2 = 1 TO iDim2Extent: MESSAGE "iArray[" iDim1 "," iDim2 "]" " = " iArray[ iDim2 + (iDim1 - 1) * iDim2Extent ] VIEW-AS ALERT-BOX. END. END. |
A series of terms and operators in an expression, with no grouping parentheses (‘(' and ‘)'), evaluate in an order of precedence determined by the operators. Thus, operators of higher precedence evaluate before operators of lower precedence, and operators of the same precedence evaluate in order from left to right. Otherwise, a series of terms and operators within a particular grouping parentheses evaluate according to their precedence before any series of terms and operators outside that grouping parentheses. The following table shows the order of precedence for ABL operators identified by function and symbol.
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Precedence (highest to lowest)
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Operator function
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Symbol
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11
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Numeric negative (unary)
Numeric positive (unary)
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-
+
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10
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Numeric modulo
Numeric division
Numeric multiplication
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MODULO
/
*
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9
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Date subtraction
Datetime subtraction
Numeric subtraction
Date addition
Datetime addition
Numeric addition
String concatenation
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-
-
-
+
+
+
+
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8
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Relational string match
Relational less than
Relational less than or equal to
Relational greater than
Relational greater than or equal to
Relational equal to
Relational not equal to
Relational string beginning
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MATCHES
LT or <
LE or <=
GT or >
GE or >=
EQ or =
NE or <>
BEGINS
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7
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Bitwise NOT (unary)
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NOT
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6
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Logical NOT (unary)
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NOT
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5
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Bitwise AND
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AND
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4
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Bitwise XOR
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XOR
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3
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Bitwise OR (inclusive)
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OR
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2
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Logical AND
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AND
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1
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Logical OR (inclusive)
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OR
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If you do not include any white space in expressions, ABL does not distinguish between a hyphen (-) used as an operator and a hyphen used as part of an ABL built-in or user-defined element name. In order to enable ABL to identify a hyphen used as an operator, you must add at least one space between the hyphen and the term or terms that the operator evaluates.
An expression of the appropriate data type can appear as a variable option of any ABL statement that takes an expression, except where specified. Expressions commonly appear in the Assignment (=) statement, ASSIGN statement, and as arguments to INPUT parameters of procedures, functions, and methods (Parameter passing syntax). Expressions cannot appear where a variable syntax option accepts only a quoted string, a user-defined name (such as a procedure or variable name), or a compile-time constant. Other restrictions might also apply.
You cannot directly reference a BLOB or CLOB database or temp-table field as a term in an expression, except as specifically provided in a given ABL statement or built-in function. Generally, you must first convert the BLOB or CLOB to a MEMPTR or LONGCHAR data type using the COPY-LOB statement, then use the result in the expression.
When a run-time error occurs in any part of an expression, the AVM stops evaluating the expression and raises the ERROR condition on the statement that contains the expression. If the error occurs in a basic term of the expression, because the AVM first evaluates all the basic terms of an expression from left to right, all such terms (especially, methods and functions) prior to the term that raises ERROR will complete execution. However, any data element set to receive the result of the expression evaluation remains unchanged, for example, when the expression is on the right-hand side of an Assignment (=) statement or is passed to an INPUT parameter. The ERROR condition from an expression can be handled, like any statement error, as appropriate for the specified statement and block error processing, including use of statement NO-ERROR options, ON ERROR phrases, and CATCH statements to handle any error messages and error objects returned from the expression. For more information, see OpenEdge Development: Error Handling.