FClose()
FCount()
FCreate()
FErase()
FError()
FieldBlock()
FieldName()
FieldPos()
FieldPut()
Tag Archives: FIELDWBLOCK()
Variable Management Functions
Variable Management
| FieldBlock | Return a code block that sets/gets a value for a given field |
| FieldWBlock | Return a sets/gets code block for field in a given work area |
| HB_AParams | Returns an array containing values of all parameters passed to a function, method or procedure |
| HB_ArgC | Returns the number of command line arguments |
| HB_ArgCheck | Checks existence of an internal switch on the command line |
| HB_ArgShift | Updates HB_Arg* parameter list removing the 1-st one and replacing it by others |
| HB_ArgString | Retrieves the vale of an internal switch set on the command line. |
| HB_ArgV | Retrieves the value of a command line argument |
| HB_PIsByRef | Determine if a parameter is passed by reference. |
| HB_PValue | Retrieves the value of an argument. |
| HB_ValToStr | Converts any scalar type to a string. |
| MemVarBlock | Returns a codeblock that sets/gets a value of memvar variable |
| PCount | Retrieves the number of arguments passed to a function. |
| Type | Retrieves the type of an expression |
| ValType | Retrieves the data type of an expression |
FieldWBlock()
FIELDWBLOCK()
Return a sets/gets code block for field in a given work area
Syntax
FIELDWBLOCK( <cFieldName>, <nWorkArea> ) --> bFieldBlock
Arguments
<cFieldName> is a string that contain the field name.
<nWorkArea> is the work area number in which <cFieldName> exist.
Returns
FIELDWBLOCK() return a code block that when evaluate could retrieve field value or assigning a new value for a field in a given work area. If <cFieldName> is not specified or from type other than character, or if <nWorkArea> is not specified or is not numeric FIELDWBLOCK() return NIL.
Description
FIELDWBLOCK() return a code block that sets/gets the value of field from a given work area. When this code block is evaluated without any parameters passed then it returns the current value of the given field. If the code block is evaluated with a parameter, than its value is used to set a new value to the field, this value is also return by the block. If the block is evaluate and there is no field with the name <cFieldName> in work area number <nWorkArea>, the code block return NIL.
Examples
LOCAL bField
// this block work on the field "name" that exist on work area 2
bFiled := FIELDBLOCK( "name", 2 )
// open a file named One in work area 1
// that have a field named "name"
SELECT 1
USE one
// open a file named Two in work area 2
// it also have a field named "name"
SELECT 2
USE two
SELECT 1
? "Original names: ", One->name, Two->name
? "Name value for file Two :", EVAL( bField )
EVAL( bField, "Two has new name" )
? "and now: ", One->name, Two->name
Compliance
If the block is evaluate and there is no field with the name <cFieldName> in the given work area, the code block return NIL.
CA-Cl*pper would raise BASE/1003 error if the field does not exist.
Files
Library is rtl
Seealso
EVAL(), FIELDBLOCK(), MEMVARBLOCK()
FieldBlock()
FIELDBLOCK()
Return a code block that sets/gets a value for a given field
Syntax
FIELDBLOCK( <cFieldName> ) --> bFieldBlock
Arguments
<cFieldName> is a string that contain the field name.
Returns
FIELDBLOCK() return a code block that when evaluate could retrieve a field value or assigning a new value to the field. If <cFieldName> is not specified or from type other than character, FIELDBLOCK() return NIL.
Description
FIELDBLOCK() return a code block that sets/gets the value of field. When this code block is evaluated without any parameters passed then it returns the current value of the given field. If the code block is evaluated with a parameter, than its value is used to set a new value to the field, this value is also return by the block. If the block is evaluate and there is no field with the name <cFieldName> in the current work area, the code block return NIL.
Note that FIELDBLOCK() works on the current work area, if you need a specific work area code block use FIELDWBLOCK() instead.
Examples
// open a file named Test that have a field named "name"
LOCAL bField
bFiled := FIELDBLOCK( "name" )
USE Test
? "Original value of field 'name' :", EVAL( bField )
EVAL( bField, "Mr X new name" )
? "New value for the field 'name' :", EVAL( bField )
Compliance
If the block is evaluate and there is no field with the name <cFieldName> in the current work area, the code block return NIL.
CA-Cl*pper would raise BASE/1003 error if the field does not exist.
Files
Library is rtl
Seealso
EVAL(), FIELDWBLOCK(), MEMVARBLOCK()
SP_WORKBLOCK
WORKBLOCK() Short: ------ WORKBLOCK() Returns a set-get block for field named in an expression Returns: -------- <bBlock> => a set-get block Syntax: ------- WORKBLOCK(cExpress) Description: ------------ Determines the work area and field name in <cExpress> and returns a FIELDWBLOCK() created block for it. Examples: --------- cExpr := "CUSTOMER->LNAME" bExpr := WORKBLOCK(cExpr) ?eval(bExpr) // displays value ?eval(bExpr,"SMITH") // sets new value Source: ------- S_FIELDS.PRG
C5_FIELDWBLOCK
FIELDWBLOCK()
Return a set-get code block for a field in a given work area
------------------------------------------------------------------------------
Syntax
FIELDWBLOCK(<cFieldName>, <nWorkArea>)
--> bFieldWBlock
Arguments
<cFieldName> is the name of the field specified as a character
string.
<nWorkArea> is the work area number where the field resides
specified as a numeric value.
Returns
FIELDWBLOCK() returns a code block that, when evaluated, sets (assigns)
or gets (retrieves) the value of <cFieldName> in the work area
designated by <nWorkArea>. If <cFieldName> does not exist in the
specified work area, FIELDWBLOCK() returns an empty block.
Description
FIELDWBLOCK() is a database function that builds a code block. When
evaluated with the EVAL() function, the code block first selects the
designated <nWorkArea>. If an argument was passed, the code block then
assigns the value of the argument to <cFieldName>. If no argument was
passed, the code block retrieves the value of <cFieldName>. The
original work area is then reselected before the code block returns
control.
Note that the specified field variable may not exist when the code block
is created but must exist before the code block is executed.
Notes
. FIELDWBLOCK() is similar to FIELDBLOCK(), except that
FIELDBLOCK() incorporates a fixed work area into the set-get block.
Examples
. This example compares FIELDWBLOCK() to a code block created
using the macro operator. Note that using FIELDWBLOCK() avoids the
speed and size overhead of the macro operator:
// Set-Get block for work area 1 defined with
// macro operator
bSetGet := &( "{ |setVal| IF( setVal == NIL, ;
1->FName, 1->FName := setVal ) }" )
// Set-Get block defined using FIELDWBLOCK()
// bSetGet created here is the functional
// equivalent of bSetGet above
bSetGet := FIELDWBLOCK("FName", 1)
Files Library is CLIPPER.LIB.
See Also: FIELDBLOCK() MEMVARBLOCK()
Code blocks, inside and out
Code blocks, inside and out
Code blocks: what, where, and why?
C5 Database Functions
AFIELDS() :
Fill arrays with the structure of the current database file
AFIELDS([<aFieldNames>],
[<aTypes>],
[<aWidths>],
[<aDecimals>]) --> nFields
ALIAS() :
Return a specified work area alias
ALIAS([<nWorkArea>]) --> cAlias
BOF() :
Determine when beginning of file is encountered
BOF() --> lBoundary
DBAPPEND() :
Add a new record
DBAPPEND() --> NIL
DBCLEARFILTER() :
Clear a filter condition
DBCLEARFILTER() –> NIL
DBCLEARIND() : Close all indexes for the current work area
DBCLEARINDEX() --> NIL
DBCLEARREL() :
Clear active relations
DBCLEARRELATION() --> NIL
DBCLOSEALL() :
Close all occupied workareas
DBCLOSEALL() --> NIL
DBCLOSEAREA() :
Close a workarea
DBCLOSEAREA() --> NIL
DBCOMMIT() :
Flush pending updates
DBCOMMIT() --> NIL
DBCOMMITALL() :
Flush pending updates in all workareas
DBCOMMITALL() --> NIL
DBCREATE() :
Create a database file from a database structure array
DBCREATE(<cDatabase>, <aStruct> [, <cDriver> ] ) --> NIL
DBCREATEIND() :
Create an Index
DBCREATEINDEX(<cIndexName>, <cKeyExpr>,
[<bKeyExpr>], [<lUnique>]) --> NIL
DBDELETE() :
Mark a record for deletion
DBDELETE() --> NIL
DBEDIT() :
Browse records in a table layout
DBEDIT([<nTop>], [<nLeft>],
[<nBottom>], <nRight>],
[<acColumns>],
[<cUserFunction>],
[<acColumnSayPictures> | <cColumnSayPicture>],
[<acColumnHeaders> | <cColumnHeader>],
[<acHeadingSeparators> | <cHeadingSeparator>],
[<acColumnSeparators> | <cColumnSeparator>],
[<acFootingSeparators> | <cFootingSeparator>],
[<acColumnFootings> | <cColumnFooting>]) --> NIL
DBEVAL() :
Evaluate a code block for each record
DBEVAL(<bBlock>,
[<bForCondition>],
[<bWhileCondition>],
[<nNextRecords>],
[<nRecord>],
[<lRest>]) --> NIL
DBF()* :
Return current alias name
DBF() --> cAlias
DBFIELDINFO() :
Return and optionally change information about a field
DBFIELDINFO(<nInfoType>,
<nFieldPos>,
[<expNewSetting>]) --> uCurrentSetting
DBFILEGET() :
Insert the contents of a field into a file
DBFILEGET(<nFieldPos>, <cTargetFile>, <nMode>)
--> lSuccess
DBFILEPUT() :
Insert the contents of a file into a field
DBFILEPUT(<nFieldPos>, <cSourceFile>)
--> lSuccess
DBFILTER() :
Return the current filter expression as a character string
DBFILTER() --> cFilter
DBGOBOTTOM() :
Move to the last logical record
DBGOBOTTOM() --> NIL
DBGOTO() :
Move to a particular record
DBGOTO(<nRecordNumber>) --> NIL
DBGOTOP() :
Move to the first logical record
DBGOTOP() --> NIL
DBINFO() :
Return and optionally change database file information
DBINFO(<nInfoType>, [<expNewSetting>])
--> uCurrentSetting
DBORDERINFO() : Return and optionally change information about orders and index files
DBORDERINFO(<nInfoType>, [<cIndexFile>],
[<cOrder> | <nPosition>],
[<expNewSetting>]) --> uCurrentSetting
DBRECALL() :
Reinstate a record marked for deletion
DBRECALL() --> NIL
DBRECORDINFO() :
Return and optionally change information about a record
DBRECORDINFO(<nInfoType>,
[<nRecord>],
[<expNewSetting>]) --> uCurrentSetting
DBREINDEX() :
Recreate all active indexes for the current work area
DBREINDEX() --> NIL
DBRELATION() :
Return the linking expression of a specified relation
DBRELATION( <nRelation> ) --> cLinkExp
DBRLOCK() :
Lock the record at the current or specified identity
DBRLOCK([<xIdentity>]) --> lSuccess
DBRLOCKLIST() Return an array of the current lock list
DBRLOCKLIST() --> aRecordLocks
DBRSELECT() :
Return the target workarea number of a relation
DBRSELECT( <nRelation> ) --> nWorkArea
DBRUNLOCK()
Release all or specified record locks
DBRUNLOCK([<xIdentity>]) --> NIL
DBSEEK() :
Search for a key value
DBSEEK(<expKey>, [<lSoftSeek>]) --> lFound
DBSELECTAR() :
Change the current workarea
DBSELECTAREA(<nArea> | <cAlias>) --> NIL
DBSETDRIVER() :
Set the default database driver
DBSETDRIVER([<cDriver>]) --> cCurrentDriver
DBSETFILTER() :
Set a filter condition
DBSETFILTER(<bCondition>, [<cCondition>]) --> NIL
DBSETINDEX()
Empty orders from an order bag into the order list
DBSETINDEX(<cOrderBagName>) --> NIL
DBSETORDER()
Set the controlling order
DBSETORDER(<nOrderNum>) --> NIL
DBSETRELAT() :
Relate two workareas
DBSETRELATION( <nArea> | <cAlias>, <bExpr>, [<cExpr>]) --> NIL
DBSKIP() :
Move relative to the current record
DBSKIP([<nRecords>]) --> NIL
DBSTRUCT() :
Create an array containing the structure of a database file
DBSTRUCT() --> aStruct
DBUNLOCK()
Release all locks for the current work area
DBUNLOCK() --> NIL
DBUNLOCKALL()
Release all locks for all work areas
DBUNLOCKALL() --> NIL
DBUSEAREA() :
Use a database file in a workarea
DBUSEAREA( [<lNewArea>],
[<cDriver>],
<cName>,
[<xcAlias>],
[<lShared>],
[<lReadonly>]) --> NIL
DELETED() :
Return the deleted status of the current record
DELETED() --> lDeleted
EOF() :
Determine when end of file is encountered
EOF() --> lBoundary
FCOUNT() :
Return the number of fields in the current (.dbf) file
FCOUNT() --> nFields
FIELD() :
Return a field name from the current (.dbf) file
FIELD/FIELD(<nPosition>) --> cFieldName
FIELDBLOCK() :
Return a set-get code block for a field variable
FIELDBLOCK(<cFieldName>) --> bFieldBlock
FIELDGET() :
Retrieve the value of a field using the ordinal position of the field in the database structure
FIELDGET(<nField>) --> ValueField
FIELDNAME() :
Return a field name from the current (.dbf) file
FIELDNAME/FIELD(<nPosition>) --> cFieldName
FIELDPOS() :
Return the position of a field in a workarea
FIELDPOS(<cFieldName>) --> nFieldPos
FIELDPUT() :
Set the value of a field variable using the ordinal position of the field in the database structure
FIELDPUT(<nField>, <expAssign>) --> ValueAssigned
FIELDWBLOCK() :
Return a set-get block for a field in a given workarea
FIELDWBLOCK(<cFieldName>, <nWorkArea>) --> bFieldWBlock
FLOCK() :
Lock an open and shared database file
FLOCK() –> lSuccess
FOUND() :
Determine if the previous search operation succeeded
FOUND() --> lSuccess
HEADER() :
Return the current database file header length
HEADER() --> nBytes
LASTREC() :
Determine the number of records in the current (.dbf) file
LASTREC() | RECCOUNT()* --> nRecords
LUPDATE() :
Return the last modification date of a (.dbf) file
LUPDATE() --> dModification
RECCOUNT()* :
Determine the number of records in the current (.dbf) file
RECCOUNT()* | LASTREC() --> nRecords
RECNO() :
Return the current record number of a work area
RECNO() --> nRecord
RECSIZE() :
Determine the record length of a database (.dbf) file
RECSIZE() --> nBytes
RLOCK()
Lock the current record in the active work area
RLOCK() --> lSuccess
SELECT() :
Determine the work area number of a specified alias
SELECT([<cAlias>]) --> nWorkArea
USED() :
Determine if a database file is in USE
USED() --> lDbfOpen
