如何以十六進制數字打印前導零

是否有更好的方法來顯示以十六進制數字顯示前導0？我想：如何以十六進制數字打印前導零

i.to_s(16)

但

2.to_s(16) #=> "2"

，我希望"02"。我試圖打印格式：

"%02x" % i

該協會致力於2，但

"%02x" % 256 #=> "100"

，我想"0100"。所以，我想出了這個：

class Integer 
    def to_hex_string 
    ("%0x" % self).size % 2 == 0 ? "%0x" % self : "%0#{("%0x" % self).size+1}x" % self 
    end 
end

它的工作原理：

2.to_hex_string #=> "02" 
256.to_hex_string #=> "0100"

它的工作原理也與Bignumber類，但它看起來很奇怪，這樣一個簡單的請求需要這樣的伎倆。有什麼更好的想法

來源

2014-10-28 Bruno

如果你只想把一個零在號碼前面，嘗試' 「0＃{i.to_s（16）}」'或' 「0％X」％i'。但是這通常表示一個八進制數。常用的十六進制前綴是「0x」，可以使用「％＃x」％i「打印。 – Stefan 2014-10-28 11:15:34

感謝您的評論，但似乎to_s（16）與BigNumber – Bruno 2014-10-31 16:16:02

你正在使這種方式太複雜。如果你要打印帶前導零十六進制整數，那麼它只是

class Integer 
    def to_hex_string 
    "0#{to_s(16)}" 
    end 
end 

2.to_hex_string # => 02 
256.to_hex_string # => 0100

來源

2014-10-28 13:33:17

錯誤地確定它是這樣更容易！謝謝！ – Bruno 2014-10-28 15:17:45

但它似乎是笨號的bug。如果您嘗試使用「ff」* 192例，如果將bug轉換爲bignum並返回十六進制 – Bruno 2014-10-28 15:34:14

這個答案是錯誤的恕我直言：它總是在前面放一個0。我認爲在'2.to_hex_string' = 02的情況下OP需要0，但是'200.to_hex_string'可能應該返回「c8」而不是「0c8」，即前導0應該只加在奇數字符串長度上。 – claus 2016-11-25 09:33:30

是的，它的錯誤：

讓我們試試這個：

class Integer 
    def to_hex_string 
    "0#{to_s(16)}" 
    end 
end 

class BigNumber 
    def to_hex_string 
    "0#{to_s(16)}" 
    end 
end 

class String 
    def to_hex_string 
    self.unpack('H*').first 
    end 

    def to_bytes_string 
    unless self.size % 2 == 0 
     raise "Can't translate a string unless it has an even number of digits" 
    end 
    raise "Can't translate non-hex characters" if self =~ /[^0-9A-Fa-f]/ 
    [self].pack('H*') 
    end 

    def to_bignum 
    self.bytes.inject { |a,b| (a << 8) + b } 
    end 
end 

p a="ff"*192 # => "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" 

p bytestring=a.to_bytes_string # => "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF" 

p bytestring.to_hex_string # => "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" 

p biga=a.to_bytes_string.to_bignum # => 24103124269210325885801166060283141129120932479456889513596750390652573915918032006690850241073460496634487662808880047878624169787949583249696129878907746514552133393816252247707820779176814996768455431373878200575973458579045991094613871220995079649978156413423006776294733552816174284117941639677858703703689691092215919430542320115627584500805795878509009937148922834766466311815150638048733751822605062469928378987059710125258433244

而且BUG是在這裏：

p biga.to_hex_string # => "0ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"

哪裏這個0來自????

更令人奇怪的是，我複雜的解決方案工作：

p ("%0x" % biga).size % 2 == 0 ? "%0x" % biga : "%0#{("%0x" % biga).size+1}x" % biga # => "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"

也許中的錯誤「0＃{to_s（16）}」？

來源

2014-10-28 16:41:53 Bruno

沒人，有什麼想法？錯誤？ – Bruno 2014-11-03 12:37:33

這是我剛剛嘗試解決此問題時在Google上的第一次打擊。我不得不找到其他幾個帖子來完成我的解決方案，但我認爲這很乾淨。

class Fixnum 
    def to_hex(bits) 
    rjust = (bits/4 + (bits.modulo(4)==0 ? 0 : 1)) 
    "0x" + self.to_s(16).rjust(rjust, "0") 
    end 
end

來源

2017-09-24 11:13:56 Shareef

如何以十六進制數字打印前導零

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