0x80000000

0x80000000 is a 32-bit hexadecimal constant. In binary it is 10000000000000000000000000000000. When interpreted as an unsigned integer, it represents 2147483648; as a signed 32-bit two's complement value, it equals -2147483648, the minimum representable value known as INT_MIN.

It marks the most significant bit of a 32-bit value. In the 32-bit signed integer range, this bit serves as the sign bit, and 0x80000000 corresponds to the lower bound of the range [-2147483648, 2147483647].

Common uses include bitwise operations and flags. It is frequently used as a mask to test or set the sign bit: if (x & 0x80000000) is nonzero, x is negative in a 32-bit signed context. It can also isolate or combine high-order bits in multi-bit fields.

In software and formats that employ fixed-width integers, 0x80000000 may appear in bitfield definitions or as a reserved or high-order flag. In Windows' HRESULT convention, values beginning with 0x80000000 indicate failure codes, although 0x80000000 itself is not a standard error code.

Memory layout depends on endianness. In little-endian systems, 0x80000000 is stored as 00 00 00 80; in big-endian systems, it is stored as 80 00 00 00.