Apple iWork '09 - Manual (Page 161)

Chapter 7 Logical and Information Functions 161
Examples
If the table cell A1 is empty and cell B2 is equal to 100:
=ISBLANK(A1) returns TRUE.
=ISBLANK(B2) returns FALSE.
Related Topics
For related functions and additional information, see:
“IFERROR” on page 159
“ISERROR” on page 161
“Adding Comments Based on Cell Contents” on page 358
“Using Logical and Information Functions Together” on page 358
“Listing of Logical and Information Functions” on page 155
“Value Types” on page 36
“The Elements of Formulas” on page 15
“Using the Keyboard and Mouse to Create and Edit Formulas” on page 26
“Pasting from Examples in Help” on page 41
ISERROR
The ISERROR function returns TRUE if a given expression evaluates to an error and
FALSE otherwise.
ISERROR(any-expression)
 any-expression: An expression to be tested. any-expression can contain any value
type.
Usage Notes
It is often better to use the IFERROR function. The IFERROR function provides all the Â
functionality of ISERROR, but allows for trapping, not just identifying, the error.
Examples
If B1 is a number value and D1 evaluates to 0, then
=IF(ISERROR(B1/D1),0,B1/D1) returns 0 since division by zero results in an error.
=IFERROR(B1/D1,0) is equivalent to the previous example, but requires only one function.