ISBLANK( ) Function
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ISBLANK( ) Function

Determines whether an expression is blank.


ISBLANK(eExpression)

Parameters

eExpression

Specifies the expression for ISBLANK( ) to evaluate. eExpression can be a field in a table, a variable or array element, or an expression.

Logical. ISBLANK( ) returns True (.T.) if the expression eExpression is blank; otherwise, ISBLANK( ) returns False (.F.).

ISBLANK( ) returns True (.T.) for fields when those fields contain certain values. The following table lists the values that field types contain for ISBLANK( ) to return True.

Data type Values the field contains

Blob

Empty (0h) or contains only zero bytes, for example, 0h00, 0h000000, and so on

Character

Empty string, spaces, or no value, such as a newly appended blank record or cleared with BLANK

Date

Blank date ({ / / }) or no value, such as a newly appended blank record or cleared with BLANK

DateTime

Blank datetime ({ / / : : }) or no value, such as a newly appended blank record or cleared with BLANK

Float

No value, such as a newly appended blank record or cleared with BLANK

General

Empty, for example, no OLE object

Logical

No value, such as a newly appended blank record or cleared with BLANK

Memo

Empty, for example, no memo contents

Numeric

No value, such as a newly appended blank record or cleared with BLANK

Varbinary

Empty (0h) or contains only zero bytes, for example, 0h00, 0h000000, and so on

NoteNote

Expressions with Currency, Integer, or Double type are never blank; therefore, ISBLANK( ) always returns False (.F.) for these expression types.

To create a blank record, use the APPEND BLANK and BLANK commands. You can also use BLANK to clear data from fields in a record.

ISBLANK( ) differs from EMPTY( ) and ISNULL( ). For example, EMPTY( ) returns True (.T.) if a character expression evaluates to empty, for example, it contains spaces, tabs, carriage returns, or line feeds. ISBLANK( ) returns True (.T.) if the character expression contains only the empty string ("") or spaces.

In the following example, a table named mytable is created and a blank record is appended. ISBLANK( ) returns True (.T.) because myfield is blank. A value is placed in myfield, and ISBLANK( ) returns False (.F.) because myfield is no longer blank.

CREATE TABLE mytable FREE (myfield C(20))
APPEND BLANK  && Add new blank record
CLEAR

? ISBLANK(myfield)  && Displays .T.
REPLACE myfield WITH 'John Smith'  && Insert a value in the field
? ISBLANK(myfield)  && Displays .F.

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