Initialize and print 128-bit integers in C

This article addresses the challenge of initializing and printing 128-bit integers in C, specifically with GCC and Clang compilers. It highlights that C compilers cannot parse 128-bit integer literals directly, causing errors. The author provides a solution using a macro `U128(hi, lo)` that combines two 64-bit values via bit shifting and OR operations. Additionally, it covers printing 128-bit integers with a custom `print_u128` function, handling cross-compiler warnings by using `inttypes.h` and `PRIx64` format specifiers. The final code compiles cleanly on both GCC and Clang, offering a practical guide for developers working with extended integer types.