为什么这个 Ruby if/else 循环 运行 不止一次，而第二次只循环了一部分？
Why is this Ruby if/else loop running more than once, and only partially on the second time?
我正在创建一个方法来获取 Fixnum 输入并 return 用文字拼写出的数字。该方法在大多数情况下都有效，但对于某些输入，我会得到一些古怪的输出。
而当我窥探代码时，似乎是这行代码：
# .concat(' hundred ').concat(reference.fetch(thousands%100)).concat(' thousand ')
这只是 if/else 语句的一部分，并且 运行 自身被两次
111230.numbers_to_words() 正确 returns:
"one hundred eleven thousand two hundred thirty"
但是
111130.numbers_to_words() 错误 returns:
"one hundred eleven thousand one hundred eleven thousand hundred thirty"
"hundred eleven thousand " 是不需要的字符串元素，它是 return 从已经 运行 本身成功的 if/else 语句编辑的。
这是怎么回事？我以为 if/else 语句一次 运行 不能再处理了。是什么导致那个神秘的字符串被 returned？
class Fixnum
define_method(:numbers_to_words) do
remaining = self
output = ""
reference = { 1 => 'one', 2 => 'two', 3 => 'three', 4 => 'four', 5 => 'five', 6 => 'six', 7 => 'seven', 8 => 'eight', 9 => 'nine',
10 => 'ten', 11 => 'eleven', 12 => 'twelve', 13 => 'thirteen', 14 => 'fourteen', 15 => 'fifteen', 16 => 'sixteen', 17 => 'seventeen',
18 => 'eighteen', 19 => 'nineteen',
20 => 'twenty', 21 => 'twenty one', 22 => 'twenty two', 23 => 'twenty three', 24 => 'twenty four', 25 => 'twenty five', 26 => 'twenty six',
27 => 'twenty seven', 28 => 'twenty eight', 29 => 'twenty nine',
30 => 'thirty', 31 => 'thirty one', 32 => 'thirty two',
33 => 'thirty three', 34 => 'thirty four', 35 => 'thirty five', 36 => 'thirty six', 37 => 'thirty seven', 38 => 'thirty eight', 39 => 'thirty nine',
40 => 'forty', 41 => 'forty one', 42 => 'forty two', 43 => 'forty three', 44 => 'forty four', 45 => 'forty five', 46 => 'forty six', 47 => 'forty seven',
48 => 'forty eight', 49 => 'forty nine', 50 => 'fifty', 51 => 'fifty one', 52 => 'fifty two', 53 => 'fifty three', 54 => 'fifty four', 55 => 'fifty five',
56 => 'fifty six', 57 => 'fifty seven', 58 => 'fifty eight', 59 => 'fifty nine', 60 => 'sixty', 61 => 'sixty one', 62 => 'sixty two', 63 => 'sixty three',
64 => 'sixty four', 65 => 'sixty five', 66 => 'sixty six', 67 => 'sixty seven', 68 => 'sixty eight', 69 => 'sixty nine', 70 => 'seventy', 71 => 'seventy one',
72 => 'seventy two', 73 => 'seventy three', 74 => 'seventy four', 75 => 'seventy five', 76 => 'seventy six', 77 => 'seventy seven', 78 => 'seventy eight',
79 => 'seventy nine', 80 => 'eighty', 81 => 'eighty one', 82 => 'eighty two', 83 => 'eighty three', 84 => 'eighty four', 85 => 'eighty five',
86 => 'eighty six', 87 => 'eighty seven', 88 => 'eighty eight', 89 => 'eighty nine', 90 => 'ninety', 91 => 'ninety one', 92 => 'ninety two',
93 => 'ninety three', 94 => 'ninety four', 95 => 'ninety five', 96 => 'ninety six', 97 => 'ninety seven', 98 => 'ninety eight', 99 => 'ninety nine' }
if remaining > 0 && remaining < 1000000000000
if remaining >= 1000000000 && remaining < 1000000000000
billions = remaining/1000000000
remaining = remaining%1000000000
if billions.to_s().length() > 2 && billions >= 100 && billions%100 != 0
output = output + reference.fetch(billions/100).concat(' hundred ').concat(reference.fetch(billions%100)).concat(' billion ')
elsif billions.to_s().length() > 2 && billions >= 100
output = output.concat(reference.fetch(billions/100)).concat(' hundred ').concat(' billion ')
elsif billions.to_s().length() < 3 && billions > 0 && billions < 100
output = output.concat(reference.fetch(billions)).concat(' billion ')
else
output = output + " "
end
end
if remaining >= 1000000 && remaining < 1000000000
millions = remaining/1000000
remaining = remaining%1000000
if millions.to_s().length() > 2 && millions >= 100 && millions%100 != 0
output = output + reference.fetch(millions/100).concat(' hundred ').concat(reference.fetch(millions%100)).concat(' million ')
elsif millions.to_s().length() > 2 && millions >= 100
output = output.concat(reference.fetch(millions/100)).concat(' hundred ').concat(' million ')
elsif millions.to_s().length() < 3 && millions > 0 && millions < 100
output = output.concat(reference.fetch(millions)).concat(' million ')
else
output = output + " "
end
end
if remaining >= 1000 && remaining < 1000000 #111110
thousands = remaining/1000 #111 length is 3
remaining = remaining%1000 #110
if thousands.to_s().length() > 2 && thousands >= 100 && thousands%100 == 0
output = output + reference.fetch(thousands/100).concat(' hundred ').concat(' thousand ')
elsif thousands.to_s().length() > 2 && thousands >= 100 && thousands%100 != 0
output = output + reference.fetch(thousands/100).concat(' hundred ').concat(reference.fetch(thousands%100)).concat(' thousand ')
elsif thousands.to_s().length() < 3 && thousands > 0 && thousands < 100
output = output.concat(reference.fetch(thousands)).concat(' thousand ')
else
output = output + " "
end
end
# .concat(' hundred ').concat(reference.fetch(thousands%100)).concat(' thousand ')
if remaining >=100 && remaining < 1000
if remaining>100 && remaining<1000 && remaining%100 > 0
output = output + reference.fetch(remaining/100).concat(' hundred ').concat(reference.fetch(remaining%100))
elsif remaining>100 && remaining<1000 && remaining%100 == 0
output = output + reference.fetch(remaining/100).concat(' hundred ')
elsif remaining == 100
output = output + ('one hundred')
else
output = output + " "
end
end
if remaining < 100 && remaining > 0
output = output.concat(reference.fetch(remaining))
end
else
output = "zero"
end
output.strip().squeeze(" ")
end
end
问题是表格的所有行
reference.fetch(something).concat(" something else")
concat 修改接收者（与返回新字符串相反），因此所有这些行都在更改 reference 哈希中的值。在某些情况下，您不会多次使用散列中的任何值，因此您不会注意到问题，而在其他情况下您会注意到。
将该用法替换为
reference.fetch(something) + "something else"
会避免这种情况
您可能会考虑冻结散列中的字符串 - 这会导致此类错误引发异常，而不是默默地行为不端。
我正在创建一个方法来获取 Fixnum 输入并 return 用文字拼写出的数字。该方法在大多数情况下都有效，但对于某些输入，我会得到一些古怪的输出。
而当我窥探代码时，似乎是这行代码：
# .concat(' hundred ').concat(reference.fetch(thousands%100)).concat(' thousand ')
这只是 if/else 语句的一部分，并且 运行 自身被两次
111230.numbers_to_words() 正确 returns:
"one hundred eleven thousand two hundred thirty"
但是
111130.numbers_to_words() 错误 returns:
"one hundred eleven thousand one hundred eleven thousand hundred thirty"
"hundred eleven thousand " 是不需要的字符串元素，它是 return 从已经 运行 本身成功的 if/else 语句编辑的。
这是怎么回事？我以为 if/else 语句一次 运行 不能再处理了。是什么导致那个神秘的字符串被 returned？
class Fixnum
define_method(:numbers_to_words) do
remaining = self
output = ""
reference = { 1 => 'one', 2 => 'two', 3 => 'three', 4 => 'four', 5 => 'five', 6 => 'six', 7 => 'seven', 8 => 'eight', 9 => 'nine',
10 => 'ten', 11 => 'eleven', 12 => 'twelve', 13 => 'thirteen', 14 => 'fourteen', 15 => 'fifteen', 16 => 'sixteen', 17 => 'seventeen',
18 => 'eighteen', 19 => 'nineteen',
20 => 'twenty', 21 => 'twenty one', 22 => 'twenty two', 23 => 'twenty three', 24 => 'twenty four', 25 => 'twenty five', 26 => 'twenty six',
27 => 'twenty seven', 28 => 'twenty eight', 29 => 'twenty nine',
30 => 'thirty', 31 => 'thirty one', 32 => 'thirty two',
33 => 'thirty three', 34 => 'thirty four', 35 => 'thirty five', 36 => 'thirty six', 37 => 'thirty seven', 38 => 'thirty eight', 39 => 'thirty nine',
40 => 'forty', 41 => 'forty one', 42 => 'forty two', 43 => 'forty three', 44 => 'forty four', 45 => 'forty five', 46 => 'forty six', 47 => 'forty seven',
48 => 'forty eight', 49 => 'forty nine', 50 => 'fifty', 51 => 'fifty one', 52 => 'fifty two', 53 => 'fifty three', 54 => 'fifty four', 55 => 'fifty five',
56 => 'fifty six', 57 => 'fifty seven', 58 => 'fifty eight', 59 => 'fifty nine', 60 => 'sixty', 61 => 'sixty one', 62 => 'sixty two', 63 => 'sixty three',
64 => 'sixty four', 65 => 'sixty five', 66 => 'sixty six', 67 => 'sixty seven', 68 => 'sixty eight', 69 => 'sixty nine', 70 => 'seventy', 71 => 'seventy one',
72 => 'seventy two', 73 => 'seventy three', 74 => 'seventy four', 75 => 'seventy five', 76 => 'seventy six', 77 => 'seventy seven', 78 => 'seventy eight',
79 => 'seventy nine', 80 => 'eighty', 81 => 'eighty one', 82 => 'eighty two', 83 => 'eighty three', 84 => 'eighty four', 85 => 'eighty five',
86 => 'eighty six', 87 => 'eighty seven', 88 => 'eighty eight', 89 => 'eighty nine', 90 => 'ninety', 91 => 'ninety one', 92 => 'ninety two',
93 => 'ninety three', 94 => 'ninety four', 95 => 'ninety five', 96 => 'ninety six', 97 => 'ninety seven', 98 => 'ninety eight', 99 => 'ninety nine' }
if remaining > 0 && remaining < 1000000000000
if remaining >= 1000000000 && remaining < 1000000000000
billions = remaining/1000000000
remaining = remaining%1000000000
if billions.to_s().length() > 2 && billions >= 100 && billions%100 != 0
output = output + reference.fetch(billions/100).concat(' hundred ').concat(reference.fetch(billions%100)).concat(' billion ')
elsif billions.to_s().length() > 2 && billions >= 100
output = output.concat(reference.fetch(billions/100)).concat(' hundred ').concat(' billion ')
elsif billions.to_s().length() < 3 && billions > 0 && billions < 100
output = output.concat(reference.fetch(billions)).concat(' billion ')
else
output = output + " "
end
end
if remaining >= 1000000 && remaining < 1000000000
millions = remaining/1000000
remaining = remaining%1000000
if millions.to_s().length() > 2 && millions >= 100 && millions%100 != 0
output = output + reference.fetch(millions/100).concat(' hundred ').concat(reference.fetch(millions%100)).concat(' million ')
elsif millions.to_s().length() > 2 && millions >= 100
output = output.concat(reference.fetch(millions/100)).concat(' hundred ').concat(' million ')
elsif millions.to_s().length() < 3 && millions > 0 && millions < 100
output = output.concat(reference.fetch(millions)).concat(' million ')
else
output = output + " "
end
end
if remaining >= 1000 && remaining < 1000000 #111110
thousands = remaining/1000 #111 length is 3
remaining = remaining%1000 #110
if thousands.to_s().length() > 2 && thousands >= 100 && thousands%100 == 0
output = output + reference.fetch(thousands/100).concat(' hundred ').concat(' thousand ')
elsif thousands.to_s().length() > 2 && thousands >= 100 && thousands%100 != 0
output = output + reference.fetch(thousands/100).concat(' hundred ').concat(reference.fetch(thousands%100)).concat(' thousand ')
elsif thousands.to_s().length() < 3 && thousands > 0 && thousands < 100
output = output.concat(reference.fetch(thousands)).concat(' thousand ')
else
output = output + " "
end
end
# .concat(' hundred ').concat(reference.fetch(thousands%100)).concat(' thousand ')
if remaining >=100 && remaining < 1000
if remaining>100 && remaining<1000 && remaining%100 > 0
output = output + reference.fetch(remaining/100).concat(' hundred ').concat(reference.fetch(remaining%100))
elsif remaining>100 && remaining<1000 && remaining%100 == 0
output = output + reference.fetch(remaining/100).concat(' hundred ')
elsif remaining == 100
output = output + ('one hundred')
else
output = output + " "
end
end
if remaining < 100 && remaining > 0
output = output.concat(reference.fetch(remaining))
end
else
output = "zero"
end
output.strip().squeeze(" ")
end
end
问题是表格的所有行
reference.fetch(something).concat(" something else")
concat 修改接收者（与返回新字符串相反），因此所有这些行都在更改 reference 哈希中的值。在某些情况下，您不会多次使用散列中的任何值，因此您不会注意到问题，而在其他情况下您会注意到。
将该用法替换为
reference.fetch(something) + "something else"
会避免这种情况
您可能会考虑冻结散列中的字符串 - 这会导致此类错误引发异常，而不是默默地行为不端。