DEFINE FUNCTION
function-name
|
| [return-data-definition] |
| [function-data-definition] |
| statement... |
END-FUNCTION
|
This document covers the following topics:
For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.
The DEFINE FUNCTION statement may be used to create new
user-defined functions which may be called instead of operands in the Natural
statements. Functions can be defined inside the object type Function only.
For further information, see the following sections in the Programming Guide:
Natural object type Function
| Syntax Element | Description |
|---|---|
function-name
|
Name of Natural Function:
The name must follow the same rules as used for user-defined variables, see Naming Conventions for User-Defined Variables in the Using Natural Studio documentation. This means that the name may have a maximum length of 32 characters and may start with a letter or some special characters such as a hash (#). You may not use the same function name twice in one library
(including the libraries of the |
return-data-definition
|
Return Data
Definition Clause: For details on this clause, see
Return Data
Definition.
|
function-data-definition
|
Function Data
Definition Clause: For details on this clause, see
Function Data
Definition.
|
statement... |
Statement(s) to be Executed: In place of statement, you must supply one or several suitable statements, depending on the situation. For an example of a statement, see
Example.
|
END-FUNCTION
|
End of DEFINE FUNCTION Statement: The Natural reserved word
END-FUNCTION must be used to terminate the DEFINE
FUNCTION statement.
|
RETURNS [variable-name]
|
|
(format-length[/array-definition]) |
|
[BY VALUE]
|
|||||
| ( |
|
A |
|
[/array-definition]) | DYNAMIC |
||||
| U | |||||||||
| B | |||||||||
Syntax Element Description:
| Syntax Element | Description |
|---|---|
RETURNS |
RETURNS Clause: Each function may contain only one definition of
the return variable; that is, only one RETURNS clause is
possible.
|
variable-name
|
Return Value:
The return value may be assigned using the
The return value must not be an array. |
BY VALUE |
Return Values by Value or by Reference:
Each parameter may be defined as If you are using the |
format-length
|
Format/Length Definition: If the BY VALUE keyword is missing,
the format-length of the
RETURNS clause must match the
format-length which is returned by the
function evaluated at run time.
|
A, U or
B |
Data Type: Alphanumeric (A),
Unicode (U) or binary (B).
|
array-definition |
Array Dimension
Definition: With
array-definition, you define the lower
and upper bounds of a dimension in an array-definition. For further
information, see DEFINE DATA statement,
Array Dimension
Definition.
|
DYNAMIC |
Dynamic Variable: A parameter may be defined as
DYNAMIC. For more information on processing dynamic variables, see
Introduction to Dynamic Variables and Fields.
|
Each Function object may contain only one function data definition.
DEFINE DATA
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PARAMETER
|
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USING
parameter-data-area
|
|
|
|
||||
parameter-data-definition 
|
||||||||||
|
|
LOCAL
|
|
USING
|
|
local-data-area |
|
|
|
|
|
| parameter-data-area | ||||||||||
|
data-definition
|
||||||||||
[INDEPENDENT AIV-data-definition
]
|
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END-DEFINE
|
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When a function calls another Natural object which uses a global data area, it establishes its own global data area (GDA). Therefore, it is not possible to modify the current GDA data of the calling object. A GDA cannot be defined in the function.
Function object containing function definition:
DEFINE FUNCTION GET-FIRST-BYTE
RETURNS (A1)
DEFINE DATA PARAMETER
1 #PARA (A10)
END-DEFINE
GET-FIRST-BYTE := #PARA /* return value is assigned
END-FUNCTION
END