1 / 27

Advanced RPG

Advanced RPG. Chapter 11 Advanced Data Definition and Manipulation. Data Types. (From Chapter 3) Character Numeric Date Boolean DBCS Pointer. Data Types. Date Types and Time defaults Date: yyyy-mm-dd (10 byte) Time: hh.mm.ss (8 byte)

kohana
Download Presentation

Advanced RPG

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Advanced RPG Chapter 11 Advanced Data Definition and Manipulation

  2. Data Types • (From Chapter 3) • Character • Numeric • Date • Boolean • DBCS • Pointer

  3. Data Types • Date Types and Time defaults • Date: yyyy-mm-dd (10 byte) • Time: hh.mm.ss (8 byte) • Timestamp: yyyy-mm-dd-hh.mm.ss.mmmmmm (26 bytes) • Alternate displays are available: • *MDY, *DMY, *EUR • Set by using either DATFMT or TIMFMT keyword\ • Examples: p. 232

  4. Data Types • All date and time formats allow you to refer to them by: • *YEARS (or *Y) • *MONTHS (*M) • *DAYS (*D) • *HOURS (*H) • *MINUTES (*MN) • *SECONDS (*S) • *MSECONDS (*MS)

  5. Data Types • Op Codes: • ADDDUR: Allows you to add duration coded in Factor2 to date in Factor1, with answer going to result field. (If value is negative the duration is subtracted not added) • Example on page 233 • SUBDUR: Two uses, One to subtract a date/time duration (similar to ADDDUR), Second is to calculate the duration between two date/time units.

  6. Data Type • Op Codes: • EXTRCT: Extracts a portion of the Date, Time, or Timestamp and stores it in the result field. Factor 1 is always blank. • Cannot use EVAL op code with the – or + with date/time fields. Must use the Add/Sub Dur op code. • Also cannot determine day of week unless you compare it to a known Sunday. ie 12/31/1899

  7. Data Type • Pointer Data Types: store addresses of memory locations instead of the actual data located there. • Tells you where to find something not what is stored there. • Example P.236 • Used in the C programming language but not widely used in RPG!!

  8. Data Type • Like (field definition) • Defining a field length or type by referencing a second field that provides the definition. D NewField S LIKE(OldField) • OldField can be another D spec or a field from a file. • Can place + or – in the length to either add or subtract from the referenced size. P. 237

  9. Data Type • Field Inspection: • built-in functions and operations that let you inspect the size and properties of data items or test individual positions or bytes within a character field. • %SIZE: returns number of bytes or length of argument. (returns size not digits!!) • %LEN: returns the number of digits or characters in an expression. (char-significant digits, numeric-precision of expression)

  10. Data Type • Field Inspection: • %DECPOS: returns the number of decimal positions of a numeric variable • %ELEM: returns the number of elements in an array or table or number of occurrences in a multiple occurrence data structure. • TESTN: test to see if character field contains all numeric characters, leading blanks or all blanks • Useful in validating fields for numeric use.

  11. Data Type • Field Inspection: • TEST: checks the validity of date, time or timestamp fields. • Must specify specific type otherwise default is used. • SCAN: lets you look for a character or string of characters within a character field. • Direction is left to right and is case sensitive • %Found is turned on if successful • Result field can contain position it found string or 0 if it does not find string

  12. Data Type • Field Inspection: • %SCAN: nearly identical to SCAN operation, but lets you perfrom the scan within an expression. • Cannot search an array or use %FOUND bif • CHECK: Similar to SCAN. CHECK verifies each character in Factor 2 is among the valid characters in Factor 1; if mismatch it stores the location of the mismatch in result field. • Useful for verification of a string

  13. Data Type • Field Inspection: • CHECKR: Works exactly like CHECK but in reverse order, right to left. • Field Manipulation: • +: Concatenation Character String • If result field is to large it pads with blanks • If result field is to small it truncates on the right • %TRIM: Trim blanks at edges • %TRIML: Trim leading blanks • %TRIMR: Trim trailing blanks

  14. Data Type • Field Manipulation: • %SUBST: Extracts a character string • Can specify starting position and length • %DEC: Converts the result of an expression to a packed decimal format. • XLATE: lets you translate characers within a string to other characters. • From and To strings must be same length

  15. Data Area • Data Area Data Structure • Defined by a U in position 23 • If no name provided it is represented by LDA • Works similar to a file • Loaded when program is run • Written back to data area when program ends

  16. Data Areas • Data Areas: as/400 objects that represent storage locations used to share data between programs within a job or between jobs. • Local Data Area: created for each job • 1024 positions long, type character, initially filed with blanks. • when job ends lda is gone • p.223

  17. Data Areas • Can access Data Areas without defining them in D specs (reading into another one you do have specified). • Use *DATAARA in Factor1 • Result field contains variable to receive contents • p. 224 • Not automatically retrieved or written back to external data area, you must program this.

  18. Data Areas • *DATAARA • IN: Retrieves a data area • OUT: Writes back to data area • UNLOCK: Unlocks data area

  19. Data Type • Program Described Data Structures: allow you to subdivide fields into smaller fields. • P. 238 • Overlay keyword: subfield overlays storage of another subfield • Different way of subdividing the field. • Used to group fields from file that are not adjacent. P. 239

  20. Data Type • Externally Described Data Structures • Format defined in DDS and refer to it in D specs. • p. 240 • Multiple Occurrence Data Structures • Structure is repeated in storage by OCCURS (##) keyword. • Similar to an array or table but much more complex collection of elements.

  21. Data Type • Initializing Data Structures • Will contain blanks at start of program unless you specify initialized value. (even numeric data types!!) • Keyword INZ(value) • Or use built in *INZSR initialize subroutine.

  22. Data Type • File Information Data Structure: • special data structure defined for each file used in your program. • Contains predefined fields that can provide information to your program about the file and I/O operations. • Helpful in debugging • Keyword INFDS and name of data structure on F spec (p. 247)

  23. Data Type • File Information Data Structure: • Usefulness: • Position 1 – 8: File Name • Position 16 – 21: contain last op code used on file • Position 11 – 15: five-digit I/O Status code • 00000: no error or exception • 00002: Function key was used to end display • 00011: signals end of file on read • 00012: signals a no-record found condition on a chain • > 00999: error code • 01218 indicates a locked record • 01021 indicates attempt to write duplicate key record

  24. Data Type • Program status data structure: provide information about the program itself and about exceptions or errors that occur • similar to file with predetermined subfields that automatically acquire values during execution. • Name of Program • Job name • Who called it

  25. Data Type • Status Codes: • 00000: no error occurred • 00101: negative square root • 00102: divide by zero • 00907: decimal data error • S in position 23 of DS definition indicates a Program Status Data Structure. • p. 249

  26. Data Area • Error Handling: • Without explicit error handling within your program, any runtime error will cause the system to suspend the program and send an interactive message to the user. • (E) extender can be used p.249 • Causes program to ignore error and continue • *PSSR: built in subroutine name that is called when an error occurs p. 250 • Combines file and program handling into one area. • You can control what happens when error is encountered.

More Related