ビットシフト

明解Ｃ言語 入門編 > 7. 基本型 >

ビットシフト

Ruby

def count_bits(x)
    count = 0
    while (x != 0)
        count += 1 if (x & 1 != 0) 
        x = (x >> 1) & ~(~0 << (x.size * 8))
    end
    return count
end

def int_bits
    return count_bits(~0)
end

def print_bits(x)
    (int_bits - 1).downto(0) do |i|
        print(((x >> i) & 1) != 0 ? '1' : '0')
    end

    puts ""
end

na = 12345

print "A       = ";  print_bits(na)
print "A >> 1  = ";  print_bits(na >> 1)
print "A >> 2  = ";  print_bits(na >> 2)
print "A >> 3  = ";  print_bits(na >> 3)
print "A >> 4  = ";  print_bits(na >> 4)
puts  ""

print "A       = ";  print_bits(na)
print "A << 1  = ";  print_bits(na << 1)
print "A << 2  = ";  print_bits(na << 2)
print "A << 3  = ";  print_bits(na << 3)
print "A << 4  = ";  print_bits(na << 4)

実行結果

L:\>ruby  l:\lesson_07_057.rb

A       = 000000000000000000011000000111001

A >> 1  = 000000000000000000001100000011100

A >> 2  = 000000000000000000000110000001110

A >> 3  = 000000000000000000000011000000111

A >> 4  = 000000000000000000000001100000011
A       = 000000000000000000011000000111001

A << 1  = 000000000000000000110000001110010

A << 2  = 000000000000000001100000011100100

A << 3  = 000000000000000011000000111001000

A << 4  = 000000000000000110000001110010000