0x04030201

0x04030201 is a 32-bit hexadecimal constant often encountered in computing, programming, and data formatting. It represents the unsigned integer whose byte pattern is 04, 03, 02, 01 when written in big-endian byte order. The same 32-bit value equals 67,305,985 in decimal.

Endianness affects how this value is stored in memory. In big-endian systems, the most significant byte is stored first, so the in-memory byte sequence appears as 04 03 02 01. In little-endian systems, the least significant byte is stored first, so the memory layout is 01 02 03 04. The logical value remains 0x04030201; only the byte order in memory varies by architecture.

Because of its orderly, descending byte sequence, 0x04030201 is frequently used as a simple test vector for demonstrating endianness, byte swapping, and serialization or deserialization routines. Reversing the byte order without changing the value yields 0x01020304, illustrating how swapping operations map between different architectures or network protocols.

In practice, 0x04030201 is not a widely recognized magic number or file signature. It is primarily a debugging and teaching aid, appearing in sample code, unit tests, and discussions about how binary data is represented and manipulated across systems. Software that handles binary headers, memory dumps, or protocol messages may employ such patterns to verify correct handling of byte order and alignment.