wchIDfield

Returns the DODA field with the IDENTITY attribute set.

Declaration

  whcIDfield(FILNO datno)

Description

wchIDfield() returns which DODA field has an IDfield (IDENTITY) auto-numbering attribute set.

Where:

• datno is the data file number. In V12 the file number typedef was formally changed from COUNT, a two-byte value to FILNO, a four-byte value. Refer to this link for compatibility details. Four Byte File Numbering

IDfields requires a DAR resource (Direct Access Resource) embedded in the file. The DAR is a specialized high-speed resource.

Return

Returns the DODA index (zero based) for the IDfield (the fieldno passed into addIDfield()). On error, -1 is returned and uerr_cod is set.

See c-tree Error Codes for a complete listing of valid c-tree error values.

Example

retval = wchIDfield(fileno);
if (retval <0 ) {
printf("\tERROR: Failed to retrieve ID column with error %d\n", uerr_cod);
}
  else
         printf("Field %d is an IDENTITY column\n", retval);

Override IDENTITY Values

PUTHDR() using the ctIDfieldOverRide mode can turn on and off the ability to override the automatic IDfield values. The override is on a per user, per file basis. A nonzero hdrval turns on the override, and a zero hdrval restores the standard operation. When the override is on for a data file that supports an IDfield, then an add record operation does not fill-in the IDfield value. Whatever is passed in the record buffer is used for the IDfield. And a rewrite permits the IDfield value to change instead of generating the IDFL_CHG error. When the override is enabled, add record operations do not consume IDfield values.

See also

addIDfield(), delIDfield(), getIDfield(), resetIDfield(), IDfields - Extended support

WhichAutoSysTimeFields

Retrieve in bufptr the A_STFIELDS fields definition structure.

Type

ISAM Function

Declaration

VRLEN WhichAutoSysTimeFields(FILNO datno, pVOID bufptr, VRLEN bufsiz);

Description

• datno - the data file number. In V12 the file number typedef was formally changed from COUNT, a two-byte value to FILNO, a four-byte value. Refer to this link for compatibility details. Four Byte File Numbering
• bufptr - pointer to a buffer where to store the definition (after successful return, it can be cast to A_STFIELDS)
• bufsiz - size of the bufptr.

Return

The size of bufptr actually used.

• uerr_cod needs to be checked if an error condition occurred.
• A return value of 0 with uerr_cod 0 indicates that no field has been defined.
• uerr_cod set to VBSZ_ERR indicates bufsiz is too small. Return value contains required size.

WhichCtree

Return the current c-tree instance reference name.

Short Name

WCHCTREE()

Type

Low-Level function

Declaration

  pTEXT WhichCtree()

Description

WhichCtree() returns the active instance reference name. This is useful for displaying the active instance during program execution.

Return

WhichCtree() returns the pointer to the current instance reference name. This is the same instance reference name passed to RegisterCtree(). If there are no active instances, a NULL will be returned. See c-tree Error Codes c-tree Programmer’s Reference Guide for a complete listing of valid c-tree error values.

Example

pCTGVAR     ctWNGV;

ctWNGV = GetCtreePointer(WhichCtree());
isam_err = ctWNGV->sisam_err

See also

NextCtree(), RegisterCtree(), SwitchCtree(), UnRegisterCtree(), GetCtreePointer()

WriteData

Write fixed-length data record.

Short Name

WRTREC()

Type

Low-Level data file function

Declaration

COUNT WriteData(FILNO datno, LONG recbyt, pVOID recptr)

Description

In V12 the file number typedef was formally changed from COUNT, a two-byte value to FILNO, a four-byte value. Refer to this link for compatibility details. Four Byte File Numbering

WriteData() writes the fixed-length data record from the buffer area pointed to by recptr into record position recbyt for data file datno.

Return

See c-tree Error Codes for a complete listing of valid c-tree error values.

Example

FILNO     datno;
TEXT      recptr[1024];

if (WriteData(datno, NewData(datno), recptr))
    printf("\nCould not write record. Error #%d",uerr_cod);

Limitations

The recbyt parameter in this function is a 4-byte value capable of addressing at most 4 gigabytes. If your application supports HUGE files (greater than 4 gigabytes), you must use the ctSETHGH() and ctGETHGH() functions to set or get the high-order 4 bytes of the file offset. See also Record Offsets Under Huge File Support.

See also

ReadData(), NewData(), WriteVData()

WriteVData

Write variable-length data record.

Short Name

WRTVREC()

Type

Low-Level variable-length record function

Declaration

COUNT WriteVData(FILNO datno, LONG recbyt, pVOID recptr, VRLEN varlen)

Description

In V12 the file number typedef was formally changed from COUNT, a two-byte value to FILNO, a four-byte value. Refer to this link for compatibility details. Four Byte File Numbering

WriteVData() writes varlen bytes from the record buffer pointed to by recptr into the variable-length data record at record position recbyt for data file datno.

Return

WriteVData() may return the following errors, in addition to those for WriteData().

See c-tree Error Codes for a complete listing of valid c-tree error values.

Example

LONG      recbyt;
FILNO     datno;
TEXT      recptr[1024];

scanf("%1023s",recptr);
recbyt = NewVData(datno,strlen(recptr));
if (WriteVData(datno,recbyt,recptr,strlen(recptr)))
    printf("\nCould not write record. Error #%d", uerr_cod);

Limitations

The recbyt parameter in this function is a 4-byte value capable of addressing at most 4 gigabytes. If your application supports HUGE files (greater than 4 gigabytes), you must use the ctSETHGH() and ctGETHGH() functions to set or get the high-order 4 bytes of the file offset. See also Record Offsets Under Huge File Support.

See also

WriteData(), ReadVData()