# Negative One

A DramaticIdentity. There's normally just one on any page.

It's so much easier to shoot them down that way.

NegativeOne is the greatest of the negative integers. Sounds like an ego trip.

If using TwosComplement? arithmetic, NegativeOne has the same bit-pattern as the maximum representable unsigned machine integer.

ANSI C doesn't express it in such terms, but its rules for casting between signed and unsigned ints effectively say that "it's a no-op if you're using TwosComplement?".

And is generally represented in a computer as a string of all-set bits, or in hexadecimal as all 'F's.

As opposed to NegativeZero?, which has no representation in 2's-complement, but does in other schemes.

Well, to be exhaustive, wouldn't you need to say something about its SquareRoot? I mean, where would complexity and ChaosTheory be without imaginary numbers?
i = sqrt(-1)
Of course, engineer call it j ...

See ComplexNumbers and ComplexNumbersAreYourFriends.

The value -1 is often used in software as a special value to indicate "error", or "not applicable", or "missing value" (see ZeroMeansNull). Many people consider this to be a bad idea, a remnant of low-level programming languages and simplistic storage techniques.

The value -1 is also equal to the value TRUE in many (scripting) languages. This makes sense, if you consider that its binary equivalent has all bits set to 1 (e.g. 11111111 for a 8-bit value). So binary spoken, false equals 00000000, and true equals 11111111. (ANS ForthLanguage is an example.)

A few years ago, a questionnaire was making its way through e-mail boxes. I sent it to an old friend from college. Here is part of his response:

``` WHAT'S YOUR FAVORITE...