September 2012
Intermediate to advanced
512 pages
12h 41m
English
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.
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);}
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