Determines whether an expression evaluates to empty.
Syntax
EMPTY(eExpression)
Returns
Logical
Arguments
eExpression
Specifies the expression that EMPTY( ) evaluates.
The expression you include can be a character, numeric, date, or logical expression, or the name of a memo or general field in an open table. EMPTY( ) returns true (.T.) when expressions evaluate to the following:
| Expression type | Evaluates to |
| Character | The empty string, spaces, tabs, carriage returns, linefeeds, or any combination of these. |
| Numeric | 0 |
| Currency | 0 |
| Float | 0 |
| Integer | 0 |
| Double | 0 |
| Date | Empty (e.g. CTOD('')) |
| DateTime | Empty (e.g. CTOT('')) |
| Logical | False (.F.) |
| Memo | Empty (no contents) |
| General | Empty (no OLE object) |
| Picture | Empty (no picture) |
EMPTY( ) cannot be used to determine if a variable object reference is empty. For example, a variable can contain an object reference for a form. If the form is closed by clicking Close from the form's pop-up menu or by issuing CLEAR WINDOWS, the variable contains the null value.
The following program example demonstrates how to use TYPE( ) and ISNULL( ) to determine if a variable object reference is valid.
goMyForm = CREATEOBJECT('Form')
WAIT WINDOW IIF(TYPE('goMyForm') = 'O' AND !ISNULL(goMyForm), ;
'goMyForm has valid object reference',;
'goMyForm does not have valid object reference')
Remarks
EMPTY( ) returns true (.T.) if the expression eExpression evaluates to empty; otherwise, EMPTY( ) returns false (.F.).