AND short circuit?

yushang  wrote:  ``no need to evaluate the second expression. I'm not sure if Excel works this way. Any suggestion?``

You are correct:  the AND function evalulates all of its parameters first, then it determines to return FALSE because at least one parameter is false.  See the example below.

If you want left-to-right evaluation only as needed, implement nested-IF expressions.  For example:

IF(condition1, IF(condition2, "both true", "second false"), "first false")

Note:  Do not implement an IFS expression.  Like AND, IFS evaluates all of its parameters first, then it determines the first condition that is TRUE left-to-right.

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To demonstrate, insert a new VBA module and enter the following functions:

Function myudf1(x)

myudf1 = x
MsgBox "myudf1"
End Function

Function myudf2(x)
myudf2 = x
MsgBox "myudf2"
End Function

Then in Excel, enter 2 into B1 and 2 in C1, and enter the following formula into A1:

=AND(myUDF1(1)=B1, myUDF2(2)=C1)

Note that we see both MsgBoxes for "myudf1" and "myudf2", even though AND will return FALSE because the first condition is FALSE.

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Again with 2 in B1 and 2 in C1, enter the following formula in A1:

=IFS(myUDF1(2)=B1, 1, myUDF2(1)=C1, 2, TRUE, 3)

Note that we see both MsbBoxes for "myudf1" and "myudf2", then it returns 1 because the first condition is true.

Disclaimer:  I cannot test IFS with VBA UDFs.  IIRC, I asked someone to run the test above, and they told me those results.  LMK if your results are different.