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Functions and Expressions
Use HCL Link functions and expressions to create component rules and map rules.
External interface functions
You can use this function to retrieve data from a database from within in a map rule.
EXIT
The EXIT function allows you to interface with a function in an external library or application.
Implementing a library EXIT function
You can develop a function in a library to be executed from an EXIT function.
EXIT function's library interface
Library functions are used within an EXIT function using information contained in the EXITPARAM structure.

Functions and Expressions
Use HCL Link functions and expressions to create component rules and map rules.
- Expressions and evaluations
  The documentation provided here describes HCL Link functions and expressions. Functions and expressions are used to create component rules and map rules.
- Using functions
  A function is an expression that generates an output by performing a certain operation on one or more inputs.
- Syntax of a function
  The following is an example of a function:
- Function argument syntax
  Arguments typically have some restrictions on the expression used for that argument.
- Character-set encoding functions
  Functions that use the HCL Link EXIT architecture convert data to the native character set of the platform as part of the function call.
- General functions
  There are several general functions you can call from map rule to process input.
- Bidirectional functions
  Bidirectional languages such as Arabic and Hebrew are languages in which the text is presented to the user ordered from right to left, but numbers and Latin alphabetic strings within the text are presented left to right.
- Bit manipulation and testing functions
  You can use this function to manipulate and to test a bit in a binary number.
- Cache functions
  Use cache functions to specify a value for each of the cache variables defined for a flow, and additionally, to alter an already specified value for a cache variable.
- Conversion functions
  You can use this function to convert an expression from one datatype to another datatype.
- Date/time functions
  You can use this function to perform various operations on date and time.
- Error handling functions
  You can use this function in evaluating the type of error during map execution.
- External interface functions
  You can use this function to retrieve data from a database from within in a map rule.
  - DBLOOKUP
    The DBLOOKUP function executes an SQL statement against a database.
  - DBQUERY
    The DBQUERY function executes an SQL statement against a database.
  - DDEQUERY
    The DDEQUERY function allows you to interface to other Windows applications such as Trading Partner PC, Excel, and so forth, provided that certain criteria are met.
  - EXIT
    The EXIT function allows you to interface with a function in an external library or application.
    - Implementing a library EXIT function
      You can develop a function in a library to be executed from an EXIT function.
      - EXIT function's library interface
        Library functions are used within an EXIT function using information contained in the EXITPARAM structure.
      - Using the EXITPARAM Structure
  - GET
    You can use the GET function to retrieve data using one of the source adapters, such as a messaging system, a database, a file, and so forth, within the course of your map.
  - HASH
    Returns a hash of the input string using the specified hash function.
  - JEXIT
    The JEXIT function provides a means to interface with a method in an external Java class. Using this function, you can manipulate simple primitive types, simple objects, and complex objects.
  - PUT
    The PUT function passes data to a target adapter.
  - RUN
    The RUN function allows you to execute another compiled map from a component or map rule.
  - RENAMEFILE
    The RENAMEFILE function renames the source file to that of the destination file. If the operation succeeds, the returned value is 0; if it fails, then an operating system-specific error number is returned.
  - HARDLINKFILE
    A hard link points or references to a specific space on the hard drive. Multiple files can be hard linked to the same space in the hard drive. If some data is changed on one of the hard linked files, all the other files reflect that change. The HARDLINKFILE function returns the hard link file's command status. On successful execution of this function: 0 is returned; on failure: an operating system-specific error code is returned.
  - SOFTLINKFILE
    A soft link points to a specific file, which in turn, references to a particular location on the hard drive. The soft link, also known as symbolic link is a second file that exists independently of its target. The SOFTLINKFILE function returns the soft (symbolic) link file's command status. On successful execution of this function: 0 is returned; on failure: an operating system-specific error code is returned.
  - COPYFILE
    The COPYFILE function copies the source file to the destination file. It returns the copy file command status. On successful execution of this function: 0 is returned; on failure: an operating system-specific error code is returned.
  - SLEEP
    The SLEEP function suspends the execution of the current map until the time-out interval elapses. The time-out or sleep interval is represented in milliseconds. On successful execution of this function: 0 is returned; on failure: -1 is returned.
- Flow functions
  Use Flow functions to specify a value for each of the flow variables defined for a flow, and additionally, to alter an already specified value for a flow variable.
- Inspection functions
  You can use this function to test and inspect the object.
- Logical functions
  Logical functions provide a way to use logical conditions to display one of several values.
- Lookup and reference functions
  These function search operates by scanning the appropriate set of items in sequence, attempting to match the logical condition.
- Math and statistics functions
  Precede all MATHLIB functions with mathlib->
- Text functions
  These functions are used to convert the text item in a map rule.
- XML functions
  There are several XML functions that you can call from component rules and map rules to process input XML data.
- Custom functions
  From the Type Designer or Map Designer, you can create custom functions to call external libraries.
- Date and time format strings
  You can use the listed format strings for numbers, dates and times in functions such as the CURRENTDATETIME, FROMNUMBER, TONUMBER, FROMDATETIME, and TODATETIME.
- Number format strings
  You can create custom number formats by using the given format strings.
- RUN function return codes
  The RUN function return codes and messages might result when using the RUN function.
- Character set codes for CPACKAGE, CSERIESTOTEXT, and CTEXT
  The second argument of the CPACKAGE, CSERIESTOTEXT, and CTEXT functions specifies the character set of the output of the function. The value of the second argument (the character set of the object content), must be a valid character set code.

EXIT function's library interface

Library functions are used within an EXIT function using information contained in the EXITPARAM structure.

This method provides great flexibility for data passed to and from a map. For example, the map can pass binary data containing nulls, and there is no limitation on the length of the returned data. The method also allows functions to report additional information by providing a return code and error message.