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
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