Hacker's Delight

Preface

Caveat Emptor: The cost of software maintenance increases with the square of the programmer’s creativity.

—First Law of Programmer Creativity, Robert D. Bliss, 1992

This is a collection of small programming tricks that I have come across over many years. Most of them will work only on computers that represent integers in two’s-complement form. Although a 32-bit machine is assumed when the register length is relevant, most of the tricks are easily adapted to machines with other register sizes.

This book does not deal with large tricks such as sophisticated sorting and compiler optimization techniques. Rather, it deals with small tricks that usually involve individual computer words or instructions, such as counting the number of 1-bits ...