The following examples show various uses for data structures and how to define them.
| Example | Description |
|---|---|
| Figure 54 | Using a data structure to subdivide a field |
| Figure 55 | Using a data structure to group fields |
| Figure 56 | Using keywords QUALIFIED, LIKEDS, and DIM with data structures, and how to code fully-qualified subfields |
| Figure 57 | Data structure with absolute and length notation |
| Figure 58 | Rename and initialize an externally described data structure |
| Figure 59 | Using PREFIX to rename all fields in an external data structure |
| Figure 60 | Defining a multiple occurrence data structure |
| Figure 61 | Aligning data structure subfields |
| Figure 62 | Defining a *LDA data area data structure |
| Figure 63 | Using data area data structures (1) |
| Figure 64 | Using data area data structures (2) |
| Figure 65 | Using an indicator data structure |
| Figure 66 | Using a multiple-occurrence indicator data structure |
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * Use length notation to define the data structure subfields. * You can refer to the entire data structure by using Partno, or by * using the individual subfields Manufactr, Drug, Strength or Count. * D Partno DS D Manufactr 4 D Drug 6 D Strength 3 D Count 3 0 D *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 IFilename++SqNORiPos1+NCCPos2+NCCPos3+NCC.................................. I........................Fmt+SPFrom+To+++DcField+++++++++L1M1FrPlMnZr...... * * Records in program described file FILEIN contain a field, Partno, * which needs to be subdivided for processing in this program. * To achieve this, the field Partno is described as a data structure * using the above Definition specification * IFILEIN NS 01 1 CA 2 CB I 3 18 Partno I 19 29 Name I 30 40 Patno
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * When you use a data structure to group fields, fields from * non-adjacent locations on the input record can be made to occupy * adjacent internal locations. The area can then be referred to by * the data structure name or individual subfield name. * D Partkey DS D Location 4 D Partno 8 D Type 4 D *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 IFilename++SqNORiPos1+NCCPos2+NCCPos3+NCC.................................. I........................Fmt+SPFrom+To+++DcField+++++++++L1M1FrPlMnZr...... * * Fields from program described file TRANSACTN need to be * compared to the field retrieved from an Item_Master file * ITRANSACTN NS 01 1 C1 2 C2 I 3 10 Partno I 11 16 0Quantity I 17 20 Type I 21 21 Code I 22 25 Location I *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq.... * * Use the data structure name Partkey, to compare to the field * Item_Nbr * C : C Partkey IFEQ Item_Nbr 99 C : C*
D CustomerInfo DS QUALIFIED BASED(@)
D Name 20A
D Address 50A
D ProductInfo DS QUALIFIED BASED(@)
D Number 5A
D Description 20A
D Cost 9P 2
D SalesTransaction...
D DS QUALIFIED
D Buyer LIKEDS(CustomerInfo)
D Seller LIKEDS(CustomerInfo)
D NumProducts 10I 0
D Products LIKEDS(ProductInfo)
D DIM(10)
/free
TotalCost = 0;
for i = 1 to SalesTransation. Numproducts;
TotalCost = TotalCost + SalesTransaction.Products (i).Cost;
dsply SalesTransaction.Products (i).Cost;
endfor;
dsply ('Total cost is ' + %char(TotalCost));
/end-free
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * Define a program described data structure called FRED * The data structure is composed of 5 fields: * 1. An array with element length 10 and dimension 70(Field1) * 2. A field of length 30 (Field2) * 3/4. Divide Field2 in 2 equal length fields (Field3 and Field4) * 5. Define a binary field over the 3rd field * Note the indentation to improve readability * * * Absolute notation: * * The compiler will determine the array element length (Field1) * by dividing the total length (700) by the dimension (70) * D FRED DS D Field1 1 700 DIM(70) D Field2 701 730 D Field3 701 715 D Field5 701 704B 2 D Field4 716 730 * * Length notation: * * The OVERLAY keyword is used to subdivide Field2 * D FRED DS D Field1 10 DIM(70) D Field2 30 D Field3 15 OVERLAY(Field2) D Field5 4B 2 OVERLAY(Field3) D Field4 15 OVERLAY(Field2:16)
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++
D.....................................Keywords+++++++++++++++++++++++++++++
*
* Define an externally described data structure with internal name
* FRED and external name EXTDS and rename field CUST to CUSTNAME
* Initialize CUSTNAME to 'GEORGE' and PRICE to 1234.89.
* Assign to subfield ITMARR the DIM keyword.
* The ITMARR subfield is defined in the external description as a
* 100 byte character field. This divides the 100 byte character
* field into 10 array elements, each 10 bytes long.
* Using the DIM keyword on an externally described numeric subfield
* should be done with caution, because it will divide the field into
* array elements (similar to the way it does when absolute notation
* is used for program described subfields).
*
D Fred E DS EXTNAME(EXTDS)
D CUSTNAME E EXTFLD(CUST) INZ('GEORGE')
D PRICE E INZ(1234.89)
D ITMARR E DIM(10)*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++
D.....................................Keywords+++++++++++++++++++++++++++++
D
D extds1 E DS EXTNAME (CUSTDATA)
D PREFIX (CU_)
D Name E INZ ('Joe's Garage')
D Custnum E EXTFLD (NUMBER)
D
*
* The previous data structure will expand as follows:
* -- All externally described fields are included in the data
* structure
* -- Renamed subfields keep their new names
* -- Subfields that are not renamed are prefixed with the
* prefix string
*
* Expanded data structure:
*
D EXTDS1 E DS
D CU_NAME E 20A EXTFLD (NAME)
D INZ ('Joe's Garage')
D CU_ADDR E 50A EXTFLD (ADDR)
D CUSTNUM E 9S0 EXTFLD (NUMBER)
D CU_SALESMN E 7P0 EXTFLD (SALESMN)*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * Define a Multiple Occurrence data structure of 20 elements with: * -- 3 fields of character 20 * -- A 4th field of character 10 which overlaps the 2nd * field starting at the second position. * * Named constant 'Max_Occur' is used to define the number of * occurrences. * * Absolute notation (using begin/end positions) * D Max_Occur C CONST(20) D DDataStruct DS OCCURS (Max_Occur) D field1 1 20 D field2 21 40 D field21 22 31 D field3 41 60 * * Mixture of absolute and length notation * D DataStruct DS OCCURS(twenty) D field1 20 D field2 20 D field21 22 31 D field3 41 60
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ * Data structure with alignment: D MyDS DS ALIGN * Properly aligned subfields * Integer subfields using absolute notation. D Subf1 33 34I 0 D Subf2 37 40I 0 * Integer subfields using length notation. * Note that Subf3 will go directly after Subf2 * since positions 41-42 are on a 2-byte boundary. * However, Subf4 must be placed in positions 45-48 * which is the next 4-byte boundary after 42. D Subf3 5I 0 D Subf4 10I 0 * Integer subfields using OVERLAY. D Group 101 120A D Subf6 5I 0 OVERLAY (Group: 3) D Subf7 10I 0 OVERLAY (Group: 5) D Subf8 5U 0 OVERLAY (Group: 9) * Subfields that are not properly aligned: * Integer subfields using absolute notation: D SubfX1 10 11I 0 D SubfX2 15 18I 0 * Integer subfields using OVERLAY: D BadGroup 101 120A D SubfX3 5I 0 OVERLAY (BadGroup: 2) D SubfX4 10I 0 OVERLAY (BadGroup: 6) D SubfX5 10U 0 OVERLAY (BadGroup: 11) * Integer subfields using OVERLAY: D WorseGroup 200 299A D SubfX6 5I 0 OVERLAY (WorseGroup) D SubfX7 10I 0 OVERLAY (WorseGroup: 3) * * The subfields receive warning messages for the following reasons: * SubfX1 - end position (11) is not a multiple of 2 for a 2 byte field. * SubfX2 - end position (18) is not a multiple of 4 for a 4 byte field. * SubfX3 - end position (103) is not a multiple of 2. * SubfX4 - end position (109) is not a multiple of 4. * SubfX5 - end position (114) is not a multiple of 4. * SubfX6 - end position (201) is not a multiple of 2. * SubfX7 - end position (205) is not a multiple of 4.
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * Define a data area data structure based on the *LDA. * * Example 1: * A data area data structure with no name is based on the *LDA. * In this case, the DTAARA keyword does not have to be used. * D UDS D SUBFLD 1 600A *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ * Example 2: * This data structure is explicitly based on the *LDA using * the DTAARA keyword. Since it is not a data area data * structure, it must be handled using IN and OUT operations. * D LDA_DS DS DTAARA(*LDA) D SUBFLD 1 600A ... C IN LDA_DS C OUT LDA_DS *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ * Example 3: * This data structure is explicitly based on the *LDA using * the DTAARA keyword. Since it is a data area data * structure, it is read in during initialization and written * out during termination. It can also be handled using IN * and OUT operations, since the DTAARA keyword was used. * D LDA_DS UDS DTAARA(*LDA) D SUBFLD 1 600A ... C IN LDA_DS C OUT LDA_DS
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 HKeywords++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ H DFTNAME(Program1) H * FFilename++IPEASF.....L.....A.Device+.Keywords+++++++++++++++++++++++++++ FSALESDTA IF E DISK * DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * This program uses a data area data structure to accumulate * a series of totals. The data area subfields are then added * to fields from the file SALESDTA. D Totals UDS D Tot_amount 8 2 D Tot_gross 10 2 D Tot_net 10 2 *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 CL0N01Factor1+++++++Opcode(E)+Factor2++++++++++++++++++++++++++++++++++++++ * C : C EVAL Tot_amount = Tot_amount + amount C EVAL Tot_gross = Tot_gross + gross C EVAL Tot_net = Tot_net + net
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 HKeywords++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ H DFTNAME(Program2) *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * This program processes the totals accumulated in Program1. * Program2 then uses the total in the subfields to do calculations. * D Totals UDS D Tot_amount 8 2 D Tot_gross 10 2 D Tot_net 10 2 *.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq.... * C : C EVAL *IN91 = (Amount2 <> Tot_amount) C EVAL *IN92 = (Gross2 <> Tot_gross) C EVAL *IN93 = (Net2 <> Tot_net) C :
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 FFilename++IPEASFRLen+LKlen+AIDevice+.Keywords++++++++++++++++++++++++++ * Indicator data structure "DispInds" is associated to file "Disp". FDisp CF E WORKSTN INDDS (DispInds) DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ * * This is the indicator data structure: * D DispInds DS * Conditioning indicators for format "Query" D ShowName 21 21N * Response indicators for format "Query" D Exit 3 3N D Return 12 12N D BlankNum 31 31N * Conditioning indicators for format "DispSflCtl" D SFLDSPCTL 41 41N D SFLDSP 42 42N D SFLEND 43 43N D SFLCLR 44 44N CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq.... * * Set indicators to display the subfile: C EVAL SFLDSP = *ON C EVAL SFLEND = *OFF C EVAL SFLCLR = *OFF C EXFMT DispSFLCTL * * Using indicator variables, we can write more readable programs: C EXFMT Query C IF Exit or Return C RETURN C ENDIF
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8 FFilename++IPEASFRLen+LKlen+AIDevice+.Keywords++++++++++++++++++++++++++ * Indicator data structure "ErrorInds" is associated to file "Disp". FDisp CF E WORKSTN INDDS (ERRORINDS) DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++ D.....................................Keywords+++++++++++++++++++++++++++++ D @NameOk C 0 D @NameNotFound C 1 D @NameNotValid C 2 D @NumErrors C 2 * * Indicator data structure for ERRMSG: * D ERRORINDS DS OCCURS(@NumErrors) * Indicators for ERRMSG: D NotFound 1 1N D NotValid 2 2N * * Indicators for QUERY: D Exit 3 3N D Refresh 5 5N D Return 12 12N * * Prototype for GetName procedure (code not shown) D GetName PR 10I 0 D Name 50A CONST CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq.... * C DOU Exit or Return C EXFMT QUERY * Check the response indicators C SELECT C WHEN Exit or Return C RETURN C WHEN Refresh C RESET QUERY C ITER C ENDSL * * Check the name C EVAL RC = GetName(Name) * * If it is not valid, display an error message C IF RC <> @NameOk C RC OCCURS ErrorInds C EXFMT ERRMSG C ENDIF C ENDDO ... C *INZSR BEGSR * * Initialize the occurrences of the ErrorInds data structure C @NameNotFound OCCUR ErrorInds C EVAL NotFound = '1' C @NameNotValid OCCUR ErrorInds C EVAL NotValid = '1' C ENDSR