How can I use functions in Excel to perform information systems tasks efficiently?

Description

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

You can use an IS function to get information about a value before performing a calculation or other action with it. For example, you can use the ISERROR function in conjunction with the IF function to perform a different action if an error occurs:

=IF(ISERROR(A1), “An error occurred.”, A1 * 2)

This formula checks to see if an error condition exists in A1. If so, the IF function returns the message “An error occurred.” If no error exists, the IF function performs the calculation A1*2.

Syntax

ISBLANK(value)

ISERR(value)

ISERROR(value)

ISLOGICAL(value)

ISNA(value)

ISNONTEXT(value)

ISNUMBER(value)

ISREF(value)

ISTEXT(value)

The IS function syntax has the following argument:

• value    Required. The value that you want tested. The value argument can be a blank (empty cell), error, logical value, text, number, or reference value, or a name referring to any of these.

Remarks

• The value arguments of the IS functions are not converted. Any numeric values that are enclosed in double quotation marks are treated as text. 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 to a number 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, these functions provide a method for locating errors in formulas (see the following examples).

Examples