Variable Definition

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# Variable Definition

| scalar-definition array-definition |

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

The `variable-definition` option is used to define a single field/variable that may be single-valued (`scalar-definition`) or multi-valued (`array-definition`).

#### scalar-definition

variable-name |  | (format-length) |  |  |  | `CONSTANT` `INIT` |  | init-definition |  | [emhdpm]
( |  | `A` `U` `B` |  | ) | `DYNAMIC`
`HANDLE OF OBJECT`

#### array-definition

variable-name |  | (format-length/array-definition) |  |  |  | `CONSTANT` `INIT` |  | array-init-definition |  | [emhdpm]
( |  | `A` `U` `B` |  | /array-definition) | `DYNAMIC`
(array-definition) `HANDLE OF OBJECT`

## Syntax Description

Syntax Element | Description
--- | ---
`variable-name` | Variable Name: The name to be assigned to the variable. Rules for Natural variable names apply. With `DEFINE DATA INDEPENDENT`, the variable name must begin with a plus character (+). For information on naming conventions for user-defined variables, see Naming Conventions for User-Defined Variables in Using Natural.
`format-length` | Format/Length Definition: For information on format/length definition of user-defined variables, see Format and Length of User-Defined Variables in the Programming Guide.
`HANDLE OF OBJECT` | Handle of Object: Used in conjunction with NaturalX. A handle identifies a dialog element in code and is stored in handle variables. For further information, see NaturalX in the Programming Guide.
`A`, `U` or `B` | Data Type: Alphanumeric (A), Unicode (U) or binary (B) for dynamic variables.
`array-definition` | Array Dimension Definition: With an `array-definition` you define the lower and upper bounds of dimensions in an array-definition. For further information, see Array Dimension Definition.
`DYNAMIC` | DYNAMIC Option: A field may be defined as `DYNAMIC`. For more information on processing dynamic variables, see Introduction to Dynamic Variables and Fields.
`CONSTANT` | CONSTANT Option: The variable/array is to be treated as a named constant. The constant value(s) assigned will be used each time the variable/array is referenced. The value(s) assigned cannot be modified during program execution. See also Field Definitions, User-Defined Constants, Defining Named Constants in the Programming Guide. Notes: For reasons of internal handling, it is not allowed to mix variable definitions and constant definitions within one group definition; that is, a group may contain either variables only or constants only. The `CONSTANT` clause must not be used with `DEFINE DATA INDEPENDENT` and `DEFINE DATA CONTEXT`. The `CONSTANT` option cannot be used with X-arrays. The `CONSTANT` option must not be used with `DEFINE DATA INDEPENDENT` and `DEFINE DATA CONTEXT`.
`INIT` | INIT Option: The variable/array is to be assigned an initial value. This value will also be used when this variable/array is referenced in a `RESET INITIAL` statement. If no `INIT` specification is supplied, a field will be initialized with a default initial value depending on its format (see table Default Initial Values below). For further information, see Field Definitions, Initial Values in the Programming Guide. With `DEFINE DATA INDEPENDENT` and `DEFINE DATA CONTEXT`, the `INIT` clause is evaluated in each executed Natural object that contains this clause (not only in the Natural object that allocates the variable). This is different to the way the `INIT` works for global variables. The `INIT` option cannot be used with X-arrays.
`init-definition` | Initial-Value Definition: With the `init-definition` option, you define the initial/constant values for a variable. See Initial-Value Definition.
`array-init-definition` | Initial/Constant Values for an Array: The array is to be assigned an initial value. This value will also be used when this array is referenced in a `RESET INITIAL` statement. With an `array-init-definition`, you define the initial/constant values for an array. For further information, see Initial/Constant Values for an Array.
`emhdpm` | EM, HD, PM Parameters for Field/Variable: With this option, additional parameters to be in effect for a field/variable may be defined. For further information, see EM, HD, PM Parameters for Field/Variable.

### Default Initial Values

The following table shows the default initial values that are provided with the various formats:

Format | Default Initial Value
--- | ---
B, F, I, N, P | `0`
A, U | (blank)
L | `FALSE`
D | `D' '`
T | `T'00:00:00'`
C | (`AD``=D`)
Object Handle | `NULL-HANDLE`

Fields declared as `DYNAMIC` do not have any initial value because their field length is zero by default.