Expressions Syntax

Applies To: Microsoft Dynamics AX 2012 R3, Microsoft Dynamics AX 2012 R2, Microsoft Dynamics AX 2012 Feature Pack, Microsoft Dynamics AX 2012

An expression in X++ is used in either a mathematical or logical way. Expressions are built on the data types of the language; that is, an expression returns a value of some type. This value can be used in calculations, assignments, conditional statements, and so on.

EBNF Description of Expressions in X++

Expression	=	Simple-expression [RelationalOperator Simple-expression ]
RelationalOperator	=	= | != | < | > | <= | >= | like
Simple-expression	=	Simple-expression [ + | - | | ] Term | Term
Term	=	Compfactor { Mult-operator CompFactor }
Mult-operator	=	* | / | div | mod | << | >> | & | ^ | |
CompFactor	=	[ ! ] [ - | ~ ] Factor
Factor	=	Literal | Enum | Variable | FunctionCall | ( If-expression ) | Select-expression
Enum	=	EnumName :: Literal
Variable	=	Identifier [ [ Expression ] ] [ . Expression ]
FunctionCall	=	[ Expression (. | ::) | this . ] FunctionName ( argumentlist )
If-expression	=	Expression ? Expression : Expression

Semantic restrictions apply on the preceding syntax. You cannot call any method using the :: operator. Similarly, you cannot use the this keyword without an active object; that is, if you are not within a method and so on.

Examples

Example of expression	Description
1	An integer literal.
NoYes::No	An enum-reference.
A	A variable-reference.
Debtor::Find("1")	A static method-call (returns a customer variable).
(A > 3 ? true : false)	An if-expression that returns true or false.
(select CustTable where CustTable.Account == "100").NameRef	A select-expression. Returns the nameref field in the customer table. This is a string.
A >= B	A logical expression. Returns true or false.
A + B	An arithmetic expression. Sums A and B.
A + B / C	Calculates B/C, and then adds this to A.
~A + this.Value()	Sums binary not A and the result of the method-call Value on the object in scope (this).
Debtor::Find("1").NameRef	Returns the NameRef field of the found customer record.
Debtor::Find("1").Balance()	A method call to Balance in the customer table (Debtor::Find returns a customer). Returns the balance of the customer with account number 1.

See also

X++ Syntax

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