Hacker’s Delight, Second Edition

Footnotes

Foreword

1. Why “HAKMEM”? Short for “hacks memo”; one 36-bit PDP-10 word could hold six 6-bit characters, so a lot of the names PDP-10 hackers worked with were limited to six characters. We were used to glancing at a six-character abbreviated name and instantly decoding the contractions. So naming the memo “HAKMEM” made sense at the time—at least to the hackers.

Preface

1. One such program, written in C, is:main(){char*p=”main(){char*p=%c%s%c;(void)printf(p,34,p,34,10);}%c”;(void)printf(p,34,p,34,10);}

Chapter 2

1. A variation of this algorithm appears in [H&S] sec. 7.6.7.

2. This is useful to get unsigned comparisons in Java, which lacks unsigned integers.

3. Mathematicians name the operation monus and denote it with . The terms