IS Functions

This section describes the nine worksheet functions used for testing the type of a value or reference.

Each of these functions, referred to collectively as the IS functions, checks the type of value and returns TRUE or FALSE depending on the outcome. For example, the ISBLANK function returns the logical value TRUE if value is a reference to an empty cell; otherwise it returns FALSE.

Syntax

ISBLANK(value)

ISERR(value)

ISERROR(value)

ISLOGICAL(value)

ISNA(value)

ISNONTEXT(value)

ISNUMBER(value)

ISREF(value)

ISTEXT(value)

Value   is the value you want tested. Value can be a blank (empty cell), error, logical, text, number, or reference value, or a name referring to any of these, that you want to test.

Function	Returns TRUE if
ISBLANK	Value refers to an empty cell.
ISERR	Value refers to any error value except #N/A.
ISERROR	Value refers to any error value (#N/A, #VALUE!, #REF!, #DIV/0!, #NUM!, #NAME?, or #NULL!).
ISLOGICAL	Value refers to a logical value.
ISNA	Value refers to the #N/A (value not available) error value.
ISNONTEXT	Value refers to any item that is not text. (Note that this function returns TRUE if value refers to a blank cell.)
ISNUMBER	Value refers to a number.
ISREF	Value refers to a reference.
ISTEXT	Value refers to text.

Remarks

• The value arguments to the IS functions are not converted. For example, in most other functions where a number is required, the text value "19" is converted to the number 19. However, in the formula ISNUMBER("19"), "19" is not converted from a text value, and the ISNUMBER function returns FALSE.
• The IS functions are useful in formulas for testing the outcome of a calculation. When combined with the IF function, they provide a method for locating errors in formulas (see the following examples).

Examples

ISLOGICAL(TRUE) equals TRUE

ISLOGICAL("TRUE") equals FALSE

ISNUMBER(4) equals TRUE

Suppose C1:C5 on a worksheet of gold prices in different regions shows the following text values, number values, and error values: "Gold", "Region1", #REF!, $330.92, #N/A, respectively.

ISBLANK(C1) equals FALSE

ISERROR(C3) equals TRUE

ISNA(C3) equals FALSE

ISNA(C5) equals TRUE

ISERR(C5) equals FALSE

ISNUMBER(C4) equals TRUE (if the $330.92 was entered as a number and not as text)

ISREF(Region1) equals TRUE (if Region1 is defined as a range name)

ISTEXT(C2) equals TRUE (if Region1 is formatted as text)

On another worksheet, suppose you want to calculate the average of the range A1:A4, but you can't be sure that the cells contain numbers. The formula AVERAGE(A1:A4) returns the #DIV/0! error value if A1:A4 does not contain any numbers. To allow for this case, you can use the following formula to locate potential errors:

IF(ISERROR(AVERAGE(A1:A4)),"No Numbers",AVERAGE(A1:A4))