1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
main() { char c; char d; int nbits; c = -1; for (nbits = 1 ; nbits < 100; nbits++) { d = (1 << nbits) - 1; if (d == c) break; } if (nbits == 100) abort(); exit(0); }