ones-complement

I have recently been studying the one’s complement system of representing numbers and from what I understand there are two variants of the number 0. There is a negative zero (-0) and a positive zero (+0). My question is, on a one’s complement architecture, how exactly is this anomaly treated in C? Does C make a distinction between -0 and +0 or are both of these forms simply treated as zero. If it is the case that both +0 and -0 return TRUE when tested for zero, then I am wondering how the following sample code would work that calculates the number of set bits in an integer if we enter -0 as

What is the most reliable way to detect whether the architecture uses one's or two's complement representation in C++? You shouldn't have to worry - there aren't too many ones complement machines out there :) But the easiest thing might be to compare "-1" with ~0. 来源： https://stackoverflow.com/questions/16501091/detect-ones-or-twos-complement-architecture-in-c

Is there an easy way to produce a one's complement in python? For instance, if you take the hex value 0x9E , I need to convert it to 0x61 . I need to swap the binary 1's for 0's and 0's for 1's. It feels like this should be simple. Just use the XOR operator ^ against 0xFF: >>> hex(0x9E ^ 0xFF) '0x61' If you need to work with values larger than a byte, you could create the mask from the int.bit_length() method on your value: >>> value = 0x9E >>> mask = (1 << value.bit_length()) - 1 >>> hex(value ^ mask) '0x61' >>> value = 0x9E9E >>> mask = (1 << value.bit_length()) - 1 >>> hex(value ^ mask)

This question already has an answer here: Math.abs returns wrong value for Integer.Min_VALUE 6 answers Consider the below java code. Integer value = Integer.MIN_VALUE; System.out.println(value); value = -value; System.out.println(value); Output -2147483648 -2147483648 How the negative value of Integer.MIN_VALUE value results the same value? However the result can't be 2147483648 because the maximum value of Integer in java is 2147483647 . But want to know why -2147483648 ? What kind of bit-wise operations are happening internally? dasblinkenlight What kind of bit-wise operations are happening