This base class provides a standard interface from a Visual C++ function to a
COBOL routine that handles indexed-sequential file I/O to a database file.
If the MicroFocus NetExpress COBOL
compiler is used, the data files may be accessed with either the proprietary
indexed-sequential file system shipped with NetExpress or
Pervasive SQL. The linkage
section is as follows:
LINKAGE SECTION.
01 FUNCTION-KEY PIC S9999 USAGE COMP-5.
01 FILE-RECORD.
03 PRIMARY-KEY PIC X(key-length).
03 FILLER PIC X(rec-length).
PROCEDURE DIVISION USING FUNCTION-KEY, FILE-RECORD.
DETERMINE-KEY.
GO TO OPEN-READ, OPEN-WRITE, OPEN-BOTH, CLOSE-FILE,
START-READ, READ-NEXT, READ-RECORD, ADD-RECORD,
UPDATE-RECORD, DELETE-RECORD, COMMIT-FILE,
VALIDATE-DATA, DEPENDING ON FUNCTION-KEY.
This class must be inherited by a class that defines the variables in the
constructor. The member functions and variables are as follows:
- CDataFile::CDataFile()
- This is the constructor. It initializes the data members.
- BOOL CDataFile::Open(CString FileName, char
UserAccess)
- This member function calls the File I/O function with FileName in the
FILE-RECORD buffer. Note that the FILE-RECORD buffer will be blank filled
to 160 characters. FUNCTION-KEY will be set depending on UserAccess: R
(read) = 1, W (write) = 2, and B (both) = 3.
- void CDataFile::Close()
- This member function calls the File I/O function nothing in the FILE-RECORD
buffer. FUNCTION-KEY will be set to 4 (CLOSE-FILE).
- BOOL CDataFile::Start()
- This member function calls the File I/O function with the internal
DataRecord buffer passed to FILE-RECORD. FUNCTION-KEY will be set to 5
(START-READ).
- BOOL CDataFile::Start(char*PrimaryKey)
- This member function initializes the beginning of the internal DataRecord
with the specified PrimaryKey for KeyLength. It then calls the File I/O
function with the internal DataRecord buffer passed to FILE-RECORD.
FUNCTION-KEY will be set to 5 (START-READ). Finally, it calls
Next(PrimaryKey).
- BOOL CDataFile::Restart(BOOL StartFlag)
- This member function causes the indexed-sequential file to be restarted on
the last-used primary key. It calls the File I/O routine key FUNCTION-KEY
set to 5, calls Next() with the saved primary key, then calls Next() until the
saved record is returned into the internal DataRecord.
- BOOL CDataFile::Next()
- This member function calls the File I/O function with the internal
DataRecord buffer passed to FILE-RECORD. FUNCTION-KEY will be set to 6
(READ-NEXT).
- BOOL CDataFile::Next(char*Master)
- This member function calls Next(). It then checks the primary key
returned against that specified returning TRUE or FALSE depending on the
equality.
- BOOL CDataFile::Read()
- This member function calls the File I/O function with the internal
DataRecord buffer passed to FILE-RECORD. FUNCTION-KEY will be set to 7
(READ-RECORD).
- BOOL CDataFile::Read(char*PrimaryKey)
- This member function sets the specified primary key into the internal
DataRecord and calls Read().
- BOOL CDataFile::Add()
- This member function calls the File I/O function with the internal
DataRecord buffer passed to FILE-RECORD. FUNCTION-KEY will be set to 8
(ADD-RECORD).
- BOOL CDataFile::Update()
- This member function calls the File I/O function with the internal
DataRecord buffer passed to FILE-RECORD. FUNCTION-KEY will be set to 9
(UPDATE-RECORD).
- BOOL CDataFile::Delete()
- This member function calls the File I/O function with the internal
DataRecord buffer passed to FILE-RECORD. FUNCTION-KEY will be set to 10
(DELETE-RECORD).
- int CDataFile::DataLength
- This variable must be initialized to the length of the internal DataRecord
in bytes.
- int CDataFile::KeyLength
- This variable must be initialized to the length of the primary key at the
beginning of the internal DataRecord in bytes.
- int CDataFile::MasterLength
- This variable must be initialized to the length of the portion of the
primary key that defines the "master" or "parent" record's primary key in
bytes.
- void CDataFile::(*FILEIO)(short*, char*)
- This variable must be initialized to the address of the COBOL File I/O
routine.
- CString CDataFile::HomeDirectory
- This variable must be initialized to the path name of the directory that
contains the DATA directory that contains the actual data
file.
