Transcript RPG IV - Chapter 11 - Fox Valley Technical College

Advanced Data Definition
Chapter 11
Presentation © Copyright 2002, Bryan Meyers
Objectives
• Understand unique data types
• Perform date arithmetic
• Define, initialize, and use data structures
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Data Types
Data Class
Data Type
RPG Code
Character
Character
A
Numeric
Zoned decimal
S
Packed decimal
P
Signed integer
I
Unsigned integer
U
Binary
B
Floating point
F
Date
D
Time
T
Timestamp
Z
Boolean
Indicator
N
DBCS
Graphic
G
Unicode
C
Object
Object/class
O
Pointer
Pointer
*
Date
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Data Types and Time
• Three data types for dealing with time:
– Date (D)
– Time (T)
– Timestamp (Z)
• Date supports 8 distinct formats
– Default is *ISO
• Time supports 5 distinct formats
• Several separators are supported
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Date Formats
DATFMT
*ISO
*USA
*EUR
*JIS
*YMD
*MDY
*DMY
*JUL
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Representation
yyyy-mm-dd
mm/dd/yyyy
dd.mm.yyyy
yyyy-mm-dd
yy/mm/dd
mm/dd/yy
dd/mm/yy
yy/ddd
Example
9999-12-31
12/31/9999
31.12.9999
9999-12-31
99/12/31
12/3199
31/12/99
99/365
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Duration Codes
• Represent a duration in time
– *YEARS (*Y)
– *MONTHS (*M)
– *DAYS (*D)
– *HOURS (*H)
– *MINUTES (*MN)
– *SECONDS (*S)
– *MSECONDS (*MS)
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Duration Functions
• Convert a number to a duration
– %YEARS
– %MONTHS
– %DAYS
– %HOURS
– %MINUTES
– %SECONDS
– %MSECONDS
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Date Arithmetic
• Can perform date arithmetic using
date/time/timestamp data in an
expression with duration functions
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
/FREE
DueDate = BillDate + %DAYS(30);
EndTime = StartTime + %MINUTES(Min);
DueDate = DueDate + %YEARS(5);
StartDate = EndDate - %MONTHS(5);
StartDate = EndDate + %MONTHS(-5);
BillDate = DueDate - %DAYS(30);
DueDate = DueDate - %YEARS(5);
/END-FREE
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%DIFF Function
• Calculates the difference between
dates/times/timestamps
• Specify duration code as third argument
• Result is numeric
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
/FREE
Age = %DIFF(TodayDate:BirthDate:*YEARS);
CramTime = %DIFF(ExamDate:TodayDate:*DAYS);
/END-FREE
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%SUBDT Function
• Extracts portion of a date/time/timestamp
– Date “substring”
• Specify portion with a duration code
• Result is numeric
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
/FREE
BirthYear = %SUBDT(BirthDate:*YEARS);
LoanMonth = %SUBDT(LoanDate:*MONTHS);
/END-FREE
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Typed Literals
• Precede date/time literals with D or T
– D’1899-12-31’
– T’08.00.00’
• Format of literal must match any format
specified in H-spec DATFMT/TIMFMT
keyword
– Use *ISO format as default
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Pointer Data Types
• Two kinds of pointer data types
– Basing pointers
• Another field is BASED upon this pointer
– Procedure pointers
• Defined with PROCPTR keyword
• Used to access storage that is allocated
dynamically throughout the program
• Pointers store address of memory
locations rather than data values
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LIKE (Field Definition)
• LIKE keyword defines a field based on
the attributes of another field
– Used in D-specs
• Field can be increased or decreased in
length from the reference field
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++
D Gross
S
9 2
D NetPay
S
LIKE(Gross)
D FedTax
S
-2
LIKE(Gross)
D TotalGross
S
+4
LIKE(Gross)
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Data Structures
• Subdivide fields into subfields
• Restructure records with different field
layouts
• Change field data types
• Add a second dimension to arrays
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Defining Data Structures
• Subdivide fields into subfields
• Change field data types
• Data structure has two parts
– Data structure header
– Definition for the subfields
• DS coded in 24-25 on D spec signals the
beginning of a data structure
• Enter name of data structure in 7-21
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/Len+IDc.Keywords+++++++++++++++++++++++++++++
D OptName
DS
D SubfieldA
3 0
D SubfieldB
5 2
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OVERLAY
• OVERLAY keyword indicates that a subfield
overlays the storage of another subfield
• If the data item within parentheses is an array,
OVERLAY applies to each element of the array
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/Len+IDc.Keywords+++++++++++++++++++++++++++++
D
DS
D Phone
10 0
D AreaCode
3 0 OVERLAY(Phone)
D Exchange
3 0 OVERLAY(Phone:4)
D LocalNbr
4 0 OVERLAY(Phone:7)
//Using OVERLAY with *NEXT
D
DS
D BigArray
10
DIM(300)
D SubArray
2
OVERLAY(BigArray)
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Externally Described Data Structures
• Externally described data structures are useful
when you want to standardize a data structure
– Subfield are described as fields in a file record
format
– Not need to code them in RPG program
• Code an E in position 22
• Name the external file using the EXTNAME
keyword
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/Len+IDc.Keywords+++++++++++++++++++++++++++++
D PgmSts
E DS
EXTNAME(RefPgmSts)
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LIKEDS
• LIKEDS defines one data structure to be like another data structure
– Identical subfields
• Must qualify subfield name with data structure name
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/Len+IDc.Keywords+++++++++++++++++++++++++++++
D Contact
DS
D Name
35
D State
2
D ZipCode
10
D Customer
DS
LIKEDS(Contact)
D Vendor
DS
LIKEDS(Contact)
/FREE
Customer.Name = Vendor.Name;
/END-FREE
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Multiple Occurrence Data Structures
• Repeated data structures
• Keyword OCCURS
– Number determines how many times the
structure is repeated in storage
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/Len+IDc.Keywords+++++++++++++++++++++++++++++
D DSState
DS
OCCURS(50)
D Code
2
D Name
15
D SalesTax
4 4
D Capital
15
D LowZip
5 0
D HiZip
5 0
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%OCCUR Function
• Set occurrence
– %OCCUR function establishes which occurrence program uses
next
– Specify %OCCUR on left side of expression
• Get active occurrence
– %OCCUR retrieves active occurrence
– Specify %OCCUR on right side of expression
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
/FREE
FOR I = 1 to 50;
%OCCUR(DSState) = I;
READ StatesFile;
ENDFOR;
S = %OCCUR(DSState);
/END-FREE
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Variable Initialization
• INZ keyword will initialize to default value
of data type
– Definition specification
• *INZSR subroutine
– Invoked automatically at program start
• CLEAR and RESET operations will
reinitialize variables
– CLEAR generally zeros or blanks fields
– RESET reinitializes variables to INZ value
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File Information Data Structure
• Optional data structure for each file in your program
• Contains predefined subfields
– Information about the file and I/O operations
• Requires an F-spec INFDS keyword to name data
structure
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
FFilename++IPEASFRlen+LKlen+AIDevice+.Keywords+++++++++++++++++++++++++++++
DName+++++++++++ETDsFrom+++To/Len+IDc.Keywords+++++++++++++++++++++++++++++
FSample
UF E K
DISK
INFDS(SampleDS)
…
D SampleDS
DS
D FileName
*FILE
D FileStatus
*STATUS
D OpCode
*OPCODE
D RelRecNbr
397
400B 0
D RecCnt
156
159B 0
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Program Status Data Structure
• Provides information about program and
exceptions/errors that occur
• ‘S’ in position 23 identifies a program
status data structure
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/Len+IDc.Keywords+++++++++++++++++++++++++++++
D PSDS
SDS
D PrgStatus
*STATUS
D ErrType
40
42
D ErrCode
43
46
D JobName
244
253
D JobNumber
264
269
D UserName
354
363
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Points to Remember
• Date/time/timestamp data types can
manipulate date-related data with special
functions
• Fields can be defined relative to other
field definitions using the keyword LIKE
• You can define data structures that
represent complex definitions of a given
area of memory
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Points to Remember
• Data structures or subfields of data
structures can be initialized easily as part
of the data structure definition
• Two special data structures of predefined
subfields exist in RPG to provide
information about the status of files used
by the program or about the processing of
the program itself
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