Negatives in Binary

[Noah Kleinberg]

Originally Posted by Phalanx

In essence yes.
For a one byte field the value can be 0-255 if unsigned, or between -127 to +127 if signed.

255 = 1111 1111 (unsigned)
127 = 0111 1111 (unsigned)

-127 = 1111 1111 (signed)
+127 = 0111 1111 (signed)

Again it is about how your code wishes to deal with the field as a signed or unsigned value.

I think that in most cases (maybe it's different in fortran?), the value -127 would be represented by "1000 0001", using two's complement, which is the most common way to represent negative numbers. It's calculated by changing each 1 to a 0 and each 0 to a 1, and then adding 1 to the resulting number (read the wikipedia article linked above for more information...)

[Phalanx]

No, it doesn't matter what the language is, the representation is identical.

Fortran, Cobol, C, PL/1, Pascal, APL, ect... it's all the same internally.

[eugenebrooks]

The posts in this thread have so many errors that I am not
going to try and correct them all. I would suggest that you
download and read Chapter 6 of
http://srvhsrobotics.org/eugenebrooks/IntroCProg.pdf

There are 10 kinds of people in the world, those who
understand binary, and those who don't...

Have fun,
Eugene

[sdexp]

1111 = our team number = 15

100000000 = 256
10000000 = 128