Endianness and Byte Order

When to use

• Serializing or parsing any wire or file format where multi-byte integers cross a machine boundary: TCP/IP, UDP, CAN-over-ethernet, binary files, firmware images, RPC payloads, protocol headers.
• Writing or reviewing code that uses htonl/htons/ntohl/ntohs, or that needs 64-bit network-order conversion.
• Detecting the host byte order at compile time or at runtime.
• Converting integers to and from raw byte buffers (packing and unpacking fields of a streamed record).
• Reviewing code that memcpy/fwrites native structs or unions "as-is" onto a stream, or casts a byte pointer to uint16_t*/uint32_t*.

When not to use