0x100000000

0x100000000 is a hexadecimal literal representing the integer 4,294,967,296 in decimal. It equals 2^32 and is one more than the largest value representable with 32 bits unsigned (0xFFFFFFFF).

In computing, this value is commonly cited as the boundary of a 32-bit address space. Addresses in a typical 32-bit system range from 0x00000000 to 0xFFFFFFFF, and 0x100000000 marks the position beyond that 32-bit region. In practice, 4 GB is often cited as the conceptual maximum addressable memory on a pure 32-bit system, though actual usable RAM may be less due to hardware and system reservations.

In programming languages such as C and C++, 0x100000000 does not fit in a 32-bit unsigned int. It typically requires a 64-bit type, written as 0x100000000ULL (or a compiler-specific suffix) to avoid overflow. On 64-bit platforms, the constant is easily representable in 64-bit types as 4294967296.

Beyond hardware addresses, the number appears in discussions of binary address spaces and data sizes. IPv4, for example, has 2^32 total addresses; 0x100000000 corresponds to this complete address space. It is often used as a symbolic representation of the boundary between 32-bit and wider addressing in technical writing, software documentation, and memory-mapping contexts.