Initializing a Sort or Merge

• Creating input files.

• Accessing input files.

• Dealing with tape input.

SORT-MERGE/XL accepts one or more input files. You create these files with an editor, in a program, or from a database. You may not use $NULL as an input file.

Remember that your data items must be in a fixed format. Each data item of the same type must start in the same column. If your data is not in a fixed format, your results will be unpredictable.

   /tabchar = "%", tabs = (21,41,61)

   /verify tabchar, tabs

   tab character = "%"

   tabs = (21,41,61)

   \A

     1      Jones,%Eliza%000001%06/06/87

     2      Smith,%James%000005%06/06/87

     3      Jackson,%Johnathon%000005%06/06/87

     4      Washington,%Lois%000014%07/23/87

     5      Jackson,%Rosa%000022%08/15/87

   Jones,              Eliza               000001              06/06/87

   Smith,              James               000002              06/06/87

   Jackson,            Johnathon           000003              06/06/87

   Washington,         Lois                000004              07/23/87

   Jackson,            Rosa                000005              08/15/87

The SORT and MERGE intrinsics access input files through their file numbers. You pass the identification numbers in the inputfiles parameter of the HPSORTINIT or HPMERGEINIT intrinsic. The inputfiles parameter is an array. The last number in the array must be zero, as shown in the example below.

To get the file identification numbers, open the input files with the intrinsic HPFOPEN (or FOPEN), as in the example.

The following is from the example at the end of the chapter. The first part opens the files TEMPEMP and PERMEMP, and gets their file numbers, (tempFileNum and permFileNum). The second part puts these identification numbers in an array for the inputfiles parameter of the HPSORTINIT or HPMERGEINIT intrinsics.

   const

     designator : 2; {HPFOPEN formaldesignator= option}

     domain     : 3; {HPFOPEN file domain= option}

     access     : 11; {used later for output file}

   var

     tempFileNum  : INTEGER;    {HPFOPEN will return}

     permFileNum  : INTEGER;    { with file numbers }

     status       : INTEGER;        {error check}

     tempFile     : packed array [1..10] of CHAR;

     permFile     : packed array [1..10] of CHAR;

     permanent    : INTEGER;



   newFile := '%TEMPEMP%';

   permanent := 1;{file is permanent, in system file domain}

   HPFOPEN (tempFileNum, status, designator, tempFile,

            domain, permanent);



   PermFile := '%PERMEMP%';

   HPFOPEN (permFileNum, status, designator, permFile,

            domain, permanent);

Now that you have the file numbers, you can initialize the inputfiles parameter:

   var

     inputfiles   : array [1..3] of INTEGER;

        .

        .

        .

   inputfiles[1] :=  tempFileNum;  {from HPFOPEN}

   inputfiles[2] :=  permFileNum:  {from HPFOPEN}

   inputfiles[3] :=  0;   {last is always zero}

If you do not specify anything in inputfiles in HPSORTINIT, SORT/XL assumes that input will be by individual record and that you are using the HPSORTINPUT intrinsic. For information about input by record, refer to Chapter 3.

If any of your files are stored on tape, HPSORTINIT needs to know the total number of records that you have on disc and tape. This is specified in the numrecs parameter. If you have tape files but do not specify this parameter, SORT/XL defaults to 10,000 records per tape file. SORT/XL takes the size of your disc files from the file label; if all your files are on disc, do not specify this parameter.

• Creating the Output File.

• Output Record Format (SORT/XL).

• Output Record Format (MERGE/XL).

You specify the output file by indicating its file identification number in the outputfile parameter in HPSORTINIT or HPMERGEINIT. The outputfile parameter is an array. The last number in the array must be zero, as shown in the example below.

To get the file number, open the output file with HPFOPEN (or FOPEN), as in the example.

The following is from the example at the end of the chapter. The first part creates a new permanent file named outFile with WRITE access and with logical records of 80 bytes. The second part puts the number of this file into an array for the outputfile parameter of the HPSORTINIT or HPMERGEINIT intrinsics.

   const

     designator = 2; {HPFOPEN formaldesignator= option}

     domain     = 3; {HPFOPEN file domain= option}

     access     = 11; {HPFOPEN access type option #3}

     record_size= 19;  {HPFOPEN record length option #3}

   var

     outFileNum   : INTEGER;

     status       : INTEGER;

     outFile      : packed array [1..10] of CHAR;

     new          : INTEGER;

     write        : INTEGER;

     size         : INTEGER;



   new := 4;  {creates a permanent file}

   write := 1; {file is write-only access}

   size := 80;

   outFile := '%ALLEMP%';

   HPFOPEN (outFileNum, status, designator, outFile,

            domain, new, access, write, record_size, size);

Now that you have the file numbers, you can initialize the inputfiles parameter:

   var

        outputfile   : array [1..2] of INTEGER;

            .

            .

            .

   outputfile[1] :=  outFileNum; {from HPFOPEN}

   outputfile[2] :=  0;

If you do not specify anything in outputfile SORT-MERGE/XL assumes that output will be by individual record and that you are using the HPSORTOUTPUT intrinsic.

You specify the content of the SORT/XL output file with the outputoption parameter of HPSORTINIT. The part of the core routine example at the end of the chapter that specifys the outputoption in HPSORTINIT is:

   var

     OutputOption : INTEGER;

        .

        .

        .

   OutputOption := 0;  {Output record format same}

                       {  as input record format }

The options are outputoption equals:

You specify the format of the MERGE/XL output file with the keysonly parameter of HPMERGEINIT.

The part of the core routine example at the end of the chapter that specifys the keysonly in HPSORTINIT is:

   var

     keysonly : INTEGER;

        .

        .

        .

   keysonly := 0;  {output record format same as}

                   {input record format}

The options are keysonly equals:

• Beginning byte position of the key.

• Number of bytes in the key.

• Ordering sequence (0 for ascending, 1 for descending)

• Type of data to be sorted by the key. See types below:

• The data type of your input key.

• The collating sequence (sort order) you want the sort to follow.