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Eof Function (Usual)

Determine when end-of-file is encountered.

Namespace:  XSharp.RT
Assembly:  XSharp.RT (in XSharp.RT.dll) Version: 2.6
Syntax
 FUNCTION Eof(
	uArea AS USUAL
) AS LOGIC
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Parameters

uArea
Type: Usual
Specifies the work area name or number for a table from which the value must be retrieved.

Return Value

Type: Boolean
TRUE when an attempt is made to move the record pointer beyond the last logical record in a database file or if the database file contains no records; otherwise, FALSE.
If there is no database file open in the work area, EOF() returns TRUE.
Remarks
EOF() is a database function used to test for an end-of-file boundary condition when the record pointer is moving forward through a database file.
Any command that can move the record pointer can set EOF().
The most typical application is as a part of the <lCondition> argument of a DO WHILE construct that sequentially processes records in a database file.  Here <lCondition> would include a test for .NOT. EOF(), forcing the DO WHILE loop to terminate when EOF() returns TRUE.
EOF() and Found() are often used interchangeably to test whether a SEEK, FIND, or LOCATE command failed.  
With these commands, however, Found() is preferred.
When EOF() returns TRUE, the record pointer is positioned at LastRec() + 1 regardless of whether there is an active filter setting or SetDeleted() is TRUE.
Further attempts to move the record pointer forward return the same result without error.  
Once EOF() is set to TRUE, it retains its value until there is another attempt to move the record pointer.
By default, this function operates on the currently selected work area.   It can be made to operate on an unselected work area by specifying it within an aliased expression or by calling the that accepts a workarea parameter (a workarea number or alias ).
Examples
This example demonstrates EOF() by deliberately moving the record pointer beyond the last record:
X#
1USE sales
2DBGoBottom()
3QOut(EOF())            // Result: FALSE
4SKIP
5QOut(EOF())            // Result: TRUE
This example uses aliased expressions to query the value of EOF() in unselected work areas:
X#
1USE sales NEW
2USE customer NEW
3QOut(Sales->EOF())
4QOut(Customer->EOF())
This example illustrates how EOF() can be used as part of a condition for sequential database file operations:
X#
 1USE sales INDEX custnum NEW
 2DO WHILE !(Sales->EOF())
 3    nOldCust := Sales->CustNum
 4    nTotalAmount := 0
 5    DO WHILE nOldCust = Sales->CustNum .AND. ;
 6                !(Sales->EOF()
 7        QOut(Sales->CustNum, ;
 8            Sales->Description, ;
 9            Sales->SaleAmount)
10        nTotalAmount += Sales->SaleAmount
11        SKIP
12    ENDDO
13    QOut("Total amount: ", nTotalAmount)
14ENDDO
You could have written the EOF check in the code above with an alias parameter to EOF() as well:
X#
1DO WHILE !EOF("Sales")
2    .
3    .
4ENDDO
See Also