我需要能够在Ruby中确定系统的最大整数。有人知道是怎么回事吗,或者有没有可能?
发布于 2009-04-10 00:12:26
FIXNUM_MAX = (2**(0.size * 8 -2) -1)
FIXNUM_MIN = -(2**(0.size * 8 -2))
发布于 2009-02-11 23:59:48
阅读友好手册?谁会想这么做呢?
start = Time.now
largest_known_fixnum = 1
smallest_known_bignum = nil
until smallest_known_bignum == largest_known_fixnum + 1
if smallest_known_bignum.nil?
next_number_to_try = largest_known_fixnum * 1000
else
next_number_to_try = (smallest_known_bignum + largest_known_fixnum) / 2 # Geometric mean would be more efficient, but more risky
end
if next_number_to_try <= largest_known_fixnum ||
smallest_known_bignum && next_number_to_try >= smallest_known_bignum
raise "Can't happen case"
end
case next_number_to_try
when Bignum then smallest_known_bignum = next_number_to_try
when Fixnum then largest_known_fixnum = next_number_to_try
else raise "Can't happen case"
end
end
finish = Time.now
puts "The largest fixnum is #{largest_known_fixnum}"
puts "The smallest bignum is #{smallest_known_bignum}"
puts "Calculation took #{finish - start} seconds"
发布于 2009-02-11 07:18:10
在拼音中,Fixnums会自动转换为Bignums。
要找到尽可能高的Fixnum,您可以这样做:
class Fixnum
N_BYTES = [42].pack('i').size
N_BITS = N_BYTES * 8
MAX = 2 ** (N_BITS - 2) - 1
MIN = -MAX - 1
end
p(Fixnum::MAX)
厚颜无耻地从ruby-talk discussion上扯下来。请查看此处了解更多详细信息。
https://stackoverflow.com/questions/535721
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