0xFFFFFFFF

0xFFFFFFFF is a hexadecimal literal that encodes a 32-bit value with all bits set to one. In binary it is 11111111 11111111 11111111 11111111, a pattern commonly used to represent the concept of all bits active in 32-bit contexts.

In unsigned 32-bit form, 0xFFFFFFFF equals 4294967295. In signed 32-bit two's-complement form, the same bit pattern represents -1. Because of two's complement, -1 and all-ones patterns coincide in 32-bit systems. When used in languages with wider or arbitrary-precision integers, the interpretation depends on the target width and type.

Common uses include as a bitmask that preserves all 32 bits when applied with bitwise operations; as a sentinel value indicating an error, not-found, or overflow in APIs that return a 32-bit quantity. In networking, 0xFFFFFFFF corresponds to the IPv4 broadcast address 255.255.255.255. This pattern is also encountered in various protocols and low-level interfaces as a conventional all-ones value.

Practical considerations include endianness, which affects in-memory byte order but not the logical value 0xFFFFFFFF; printing or formatting may show -1 if interpreted as a signed type. Always consider the intended type (signed vs unsigned) when comparing against 0xFFFFFFFF in code.