[Info-vax] How Do You Define Record (Data Structure) Dummy Arguments in Subroutine Definitions in HP Basic for OpenVMS?

[Arne Vajhøj]

On 12/21/2019 12:55 PM, Neil Rieck wrote:
> I am assuming that "record size" in your question is referring to
> something written to disk. This depends upon the file type (in RMS,
> text files can be either "variable length" or "fixed"). Variable
> length records can be used in sequential files but not relative or
> indexed files. Click here to see three simple little hacks:

Index-sequential files can have variable length records.

Pascal:

type
   datarec  = record
                 id : [key(0)] integer;
                 data1 : integer;
                 data2 : varying [32] of char;
              end;

var
    isqf : file of datarec;

begin
    open(isqf, 'p.isq', new, organization := indexed, access_method := 
keyed);

do result in:

$ dir/full p.isq

Directory DISK2:[ARNE]

P.ISQ;1                       File ID:  (4463,26,0)
Size:           16/16         Owner:    [ARNE]
Created:    21-DEC-2019 22:14:49.49
Revised:    21-DEC-2019 22:14:49.50 (1)
...
File organization:  Indexed, Prolog: 3, Using 1 key
...
File attributes:    Allocation: 16, Extend: 0, Maximum bucket size: 2, ...
Record format:      Fixed length 44 byte records
Record attributes:  None

C:

struct datarec
{
    int id;
    int data1;
    int data2len;
    char data2[32];
};

static char *fnm = "c1.isq";
...
int main()
{
    struct FAB fab;
    struct RAB rab;
    struct XABKEY xab;
...
    long stat;
    fab = cc$rms_fab;
    fab.fab$l_fna = fnm;
    fab.fab$b_fns = strlen(fnm);
    fab.fab$b_org = FAB$C_IDX;
    fab.fab$b_rfm = FAB$C_FIX;
    fab.fab$b_rat = FAB$M_CR;
    fab.fab$l_fop = FAB$M_CIF;
    fab.fab$w_mrs = sizeof(struct datarec);
    fab.fab$b_fac = FAB$M_PUT;
    fab.fab$l_xab = (char *)&xab;
    xab = cc$rms_xabkey;
    xab.xab$b_dtp = XAB$C_STG;
    xab.xab$w_pos0 = 0;
    xab.xab$b_ref = 0;
    xab.xab$b_siz0 =sizeof(int);
    stat = sys$create(&fab,0,0);
    fab.fab$l_xab = 0;
    rab = cc$rms_rab;
    rab.rab$l_fab = &fab;
    rab.rab$b_rac = RAB$C_KEY;
    stat = sys$connect(&rab,0,0);

also gives:

$ dir/full c1.isq

Directory DISK2:[ARNE]

C1.ISQ;1                      File ID:  (4465,27,0)
Size:           16/16         Owner:    [ARNE]
Created:    21-DEC-2019 22:14:58.00
Revised:    21-DEC-2019 22:14:58.01 (1)
...
File organization:  Indexed, Prolog: 3, Using 1 key
...
File attributes:    Allocation: 16, Extend: 0, Maximum bucket size: 2, ...
Record format:      Fixed length 44 byte records
Record attributes:  Carriage return carriage control

but C:

struct datarec
{
    int id;
    int data1;
    int data2len;
    char data2[32];
};

static char *fnm = "c2.isq";
...
int main()
{
    struct FAB fab;
    struct RAB rab;
    struct XABKEY xab;
...
    long stat;
    fab = cc$rms_fab;
    fab.fab$l_fna = fnm;
    fab.fab$b_fns = strlen(fnm);
    fab.fab$b_org = FAB$C_IDX;
    fab.fab$b_rfm = FAB$C_VAR;
    fab.fab$b_rat = FAB$M_CR;
    fab.fab$l_fop = FAB$M_CIF;
    fab.fab$w_mrs = sizeof(struct datarec);
    fab.fab$b_fac = FAB$M_PUT;
    fab.fab$l_xab = (char *)&xab;
    xab = cc$rms_xabkey;
    xab.xab$b_dtp = XAB$C_STG;
    xab.xab$w_pos0 = 0;
    xab.xab$b_ref = 0;
    xab.xab$b_siz0 =sizeof(int);
    stat = sys$create(&fab,0,0);
    fab.fab$l_xab = 0;
    rab = cc$rms_rab;
    rab.rab$l_fab = &fab;
    rab.rab$b_rac = RAB$C_KEY;
    stat = sys$connect(&rab,0,0);

gives:

$ dir/full c2.isq

Directory DISK2:[ARNE]

C2.ISQ;1                      File ID:  (4467,26,0)
Size:           16/16         Owner:    [ARNE]
Created:    21-DEC-2019 22:15:06.43
Revised:    21-DEC-2019 22:15:06.44 (1)
...
File organization:  Indexed, Prolog: 3, Using 1 key
...
File attributes:    Allocation: 16, Extend: 0, Maximum bucket size: 2, ...
Record format:      Variable length, maximum 44 bytes, longest 0 bytes
Record attributes:  Carriage return carriage control

So Pascal and likely also Cobol, Fortran and Basic record structures
give you fixed length.

But direct RMS calls (necessary in C or Macro-32, possible but not
needed in above languages) you chose yourself between fixed and
variable.

Arne