Tag Archives: SET()
HB_FNameExists
HB_FNameExists
Tests for the existence of a file or a directory
Syntax
File( <cFileSpec> ) --> lExists
Argument
<cFileSpec> : Exact file name to find
Returns
<lExists> : true (.T.) if the file exists or logical false (.F.)
Description
This function return a logical true (.T.) if the given filename <cFileSpec> exist
Note
HB_FNameExists() don’t accept wildcard characters
Example
Assuming this directory tree and files exist :
C:\
| temp D
+ ---- + Dir1 D
| doc1.docx F
| test1.bat F
| test1.txt F
+ Dir2 D
doc2.docx F
test2.bat F
test2.txt F
? HB_FNameExists( 'C:\' ) // .T.
? HB_FNameExists( 'C:\*.*' ) // .F.
? HB_FNameExists( 'C:\temp\*.*' ) // .F.
? HB_FNameExists( 'C:\temp\*.' ) // .F.
? HB_FNameExists( 'C:\temp\test*.*' ) // .F.
? HB_FNameExists( 'C:\temp\test.bat' ) // .T.
? HB_FNameExists( 'C:\temp\Dir' ) // .F.
? HB_FNameExists( 'C:\temp\Dir*.*' ) // .F.
? HB_FNameExists( 'C:\temp\Dir1' ) // .T.
? HB_FNameExists( 'C:\temp\Dir1*' ) // .F.
? HB_FNameExists( 'C:\temp\Dir2' ) // .T.
? HB_FNameExists( 'C:\temp\Dir2*' ) // .F.
? HB_FNameExists( 'C:\temp\Dir1\test1.*' ) // .F.
? HB_FNameExists( 'C:\temp\Dir1\test1.bat' ) // .T.
? HB_FNameExists( 'C:\temp\Dir1\*.bat' ) // .F.
File
Library is rtl
Seealso:
SET DEFAULT, SET PATH, SET(), Directory(), File(), IsDirectory(), IsDir(), HB_FileExists(), HB_DirExists()
HB_FileExists
HB_FileExists
Tests for the existence of a file
Syntax
HB_FileExists( <cFileSpec> ) --> <lExist>
Arguments
<cFileSpec> : A character string holding the relative or absolute name of a file
Return
<lFileExist> : .T. (true) when the file <cFileSpec> exists, otherwise .F. (false) is returned.
Description
The HB_FileExists() function is used to check if a file exists that matches the specification <lFileExist>.
This is a character string containing the absolute or relative path of a file.
Note
HB_FileExists() is a Harbour level function to check for the existence of a file. This works better than FILE() in most situations, but it doesn’t accept any wildcards.
Example
Assuming this directory tree and files exist :
C:\
| temp D
+ ---- + Dir1 D
| doc1.docx F
| test1.bat F
| test1.txt F
+ Dir2 D
doc2.docx F
test2.bat F
test2.txt F
? HB_FileExists( 'C:\' ) // .F.
? HB_FileExists( 'C:\*.*' ) // .F.
? HB_FileExists( 'C:\temp\*.*' ) // .F.
? HB_FileExists( 'C:\temp\*.' ) // .F.
? HB_FileExists( 'C:\temp\test*.*' ) // .F.
? HB_FileExists( 'C:\temp\test.bat' ) // .T.
? HB_FileExists( 'C:\temp\Dir' ) // .F.
? HB_FileExists( 'C:\temp\Dir*.*' ) // .F.
? HB_FileExists( 'C:\temp\Dir1' ) // .F.
? HB_FileExists( 'C:\temp\Dir1*' ) // .F.
? HB_FileExists( 'C:\temp\Dir2' ) // .F.
? HB_FileExists( 'C:\temp\Dir2*' ) // .F.
? HB_FileExists( 'C:\temp\Dir1\test1.*' ) // .F.
? HB_FileExists( 'C:\temp\Dir1\test1.bat' ) // .T.
? HB_FileExists( 'C:\temp\Dir1\*.bat' ) // .F.
Seealso
SET DEFAULT, SET PATH, SET(), Directory(), File(), IsDirectory(), IsDir(), HB_FNameExists(), HB_DirExists()
SET MBLOCKSIZE
SET MBLOCKSIZE
Change the block size for memo files
Syntax
SET MBLOCKSIZE TO <nSize>
Arguments
<nSize> is the memo file block size in bytes. The initial memo file block size depends on the RDD. For most drivers that support the .dbt memo file format, it is 512 bytes. However, if you are using BLOB files (.dbv memo file format) via inheritance from the DBFMEMO driver, the default is 1.
Description
SET MBLOCKSIZE is functionally equivalent to calling DBINFO( DBI_MBLOCKSIZESIZE, <nSize>). Refer to this function for more information. SET MBLOCKSIZE sets the block size for the memo file associated with the database.
The block size is the minimum amount of space in bytes allocated in memo files when storing character strings in memo fields.
The initial memo block size depends on the replaceable database driver used to open a database in a work area.
The following table lists the default sizes for memo blocks of RDDs shipped with Harbour:
Default memo block sizes
Memo type Block size Changeable
--------- ---------- ----------
DBT 512 No
FPT 64 Yes
SMT 64 Yes
Examples
. The following example illustrates the SET MBLOCKSIZE command:
USE Inventor NEW
SET MBLOCKSIZE TO 256
? DBINFO(DBI_MBLOCKSIZESIZE) // Result: 256
Seealso
DBINFO(), RddSetDefault(), Set()
SET STRICTREAD
SET STRICTREAD
Toggles read optimization for database access.
Syntax
SET STRICTREAD on | OFF | ( <lOnOff> )
Arguments
on | OFF | ( <lOnOff> ) The option toggles whether or not internal memory buffers are used for loading field variables into memory variables. The default is OFF, or .F. (false). When set to ON or .T. (true), performance optimization is suppressed
Description
SET STRICTREAD is part of xHarbour’s optimization for database access. This is accomplished by means of internal memory buffers used to hold the contents of field variables. If field variables must be accessed that are held in a buffer already, no file access is required when SET STRICTREAD is set to OFF. This is the default and optimizes field access.
When SET STRICTREAD is set to ON, the contents of field variables are always read from disk.
Seealso
Set(), SET OPTIMIZE
SET AUTOSHARE
SET AUTOSHARE
Defines network detection for shared file access.
Syntax
SET AUTOSHARE TO [<nMode>]
Arguments
<nMode> A numeric value 0, 1 or 2 can be specified for <nMode>. The default is 0. If omitted, the network detection mode is switched off.
Description
SET AUTOSHARE is a compatibility command useful for changing a multi-user application to a stand-alone application by changing one line of code in the start routine of a program.
This requires changing only the value of <nMode>:
Values for SHARE mode detection
---------------------------------------------------------
Value Description
----- -------------------------------------------------
0 Disables SHARE mode detection ( default )
1 Opens database SHARED in a network, and EXCLUSIVE
if no network is detected
2 Always opens databases EXCLUSIVE
To take advantage of SET AUTOSHARE, an application must be programmed for multi-user access, respecting the rules for network programming. For example, record locks must be obtained with RLock() before changing field variables. This way, a multi-user application is created.
To change this application to a single user version, SET AUTOSHARE TO 2 is coded in the start routine.
A developer can SET AUTOMODE TO 1 on the development machine. In this case, performance advantages from EXCLUSIVE file access are available during the development cycle, while SHARED file access is granted in a multi-user environment.
Seealso
Set(), SET AUTOPEN, SET AUTORDER, USE
SET AUTORDER
SET AUTORDER
Defines the default controlling index for automatically opened index files.
Syntax
SET AUTORDER TO <nOrder>
Arguments
<nOrder> This is a numeric value specifying the ordinal position of the index to select as the controlling index when SET AUTOPEN is set to ON. The default is zero.
Description
When SET AUTOPEN is set to ON and the RDD supports automatic opening of structural indexes, the SET AUTORDER command specifies the index to activate as the controlling index. The default value for <nOrder> is zero, i.e. no controlling index is activated when an index file is automatically opened with the USE command. In this case, records of the database are accessible in physical order in the work area.
Note
Refer to SET AUTOPEN for an example of automatic selection of the controlling index.
Seealso
OrdSetFocus(), Set(), SET AUTOPEN, SET AUTOSHARE, USE
SET AUTOPEN
SET AUTOPEN
Toggles automatic opening of a structural index file
Syntax
SET AUTOPEN ON | off | (<lOnOff>)
Arguments
ON | off | (<lOnOff>) The option toggles if a structural index file is automatically opened with the USE command. With ON or .T. (true), an index file is automatically opened. OFF or .F. (false) switch this mode off.
Description
Some replaceable database drivers support automatic opening of index files with the USE command when the index file has the same file name as the database file (without extension). An example is the DBFCDX driver. SET AUTOPEN toggles this behavior.
When SET AUTOPEN is set to ON, which is the default, the USE command automatically opens an index file having the same name as the database file and the file extension returned from OrdBagExt().
Note
If an index file is automatically opened, a controlling index is not activated. The default index order is zero, i.e. records are accessible in physical order in the work area. To select a controlling index, call OrdSetFocus() or use SET AUTORDER for a default controlling index
Example
// The example demonstrates the effect of SET AUTOPEN with the
// DBFCDX driver.
REQUEST DBFCDX
PROCEDURE Main
RddSetDefault( "DBFCDX" )
SET AUTOPEN OFF
USE Customer
INDEX ON CustID TAG ID TO Customer
INDEX ON Upper(LastName+FirstName) TAG Name TO Customer
USE Customer
? OrdCount(), OrdKey() // result: 0 ""
SET AUTOPEN ON
USE Customer
? OrdCount(), OrdKey() // result: 2 ""
SET AUTORDER TO 1
USE Customer
? OrdCount(), OrdKey() // result: 2 CUSTID
? Ordkey( 2 ) // result: Upper(LastName+FirstName)
USE
RETURN
Seealso
OrdListAdd(), OrdSetFocus(), Set(), SET AUTORDER, SET AUTOSHARE, USE
