在其他人的例子的基础上,这里有一个C#实现,它将验证ISIN和CUSIP(以及其他一些Luhn变体).
用法:
foreach (var isin in ValidIsins)
{
var calculatedChecksum = SecuritiesValidation.CalculateChecksum(isin.Substring(0, 11));
var actualChecksum = (isin.Last() - '0');
Assert.AreEqual(calculatedChecksum, actualChecksum);
}
foreach (var cusip in ValidCusips)
{
var calculatedChecksum = SecuritiesValidation.CalculateChecksum(cusip.Substring(0, 8), true, true);
var actualChecksum = (cusip.Last() - '0');
Assert.AreEqual(calculatedChecksum, actualChecksum);
}
执行:
public static class SecuritiesValidation
{
public static int CalculateChecksum(IEnumerable<char> codeWithoutChecksum, bool reverseLuhn = false, bool allowSymbols = false)
{
return reverseLuhn
? codeWithoutChecksum
.Select((c, i) => c.OrdinalPosition(allowSymbols).ConditionalMultiplyByTwo(i.IsOdd()).SumDigits())
.Sum()
.TensComplement()
: codeWithoutChecksum
.ToArray()
.ToDigits(allowSymbols)
.Select((d, i) => d.ConditionalMultiplyByTwo(i.IsEven()).SumDigits())
.Sum()
.TensComplement();
}
public static bool IsChecksumCorrect(string code, bool reverseLuhn = false, bool allowSymbols = false)
{
try
{
var checksum = code.Last().ToInt();
return checksum == CalculateChecksum(code.Take(code.Length - 1), reverseLuhn, allowSymbols);
}
catch
{
return false;
}
}
/* Be careful here. This method is probably inapropriate for anything other than its designed purpose of Luhn-algorithm based validation.
* Specifically:
* - numbers are assigned a value equal to the number ('0' == 0, '1' == 1).
* - letters are assigned a value indicating the number 9 plus the letters ordinal position in the English alphabet ('A' == 10, 'B' == 11).
* - if symbols are allowed (eg: for CUSIP validation), they are assigned values beginning from 36 ('*' == 36, '@' == 37).
*/
private static int OrdinalPosition(this char c, bool allowSymbols = false)
{
if (char.IsLower(c))
return char.ToUpper(c) - 'A' + 10;
if (char.IsUpper(c))
return c - 'A' + 10;
if (char.IsDigit(c))
return c.ToInt();
if (allowSymbols)
switch (c)
{
case '*':
return 36;
case '@':
return 37;
case '#':
return 38;
}
throw new ArgumentOutOfRangeException("Specified character is not a letter, digit or allowed symbol.");
}
private static bool IsEven(this int x)
{
return (x % 2 == 0);
}
private static bool IsOdd(this int x)
{
return !IsEven(x);
}
private static int ToInt(this char digit)
{
if (char.IsDigit(digit))
return digit - '0';
throw new ArgumentOutOfRangeException("Specified character is not a digit.");
}
private static IEnumerable<int> ToDigits(this char[] s, bool allowSymbols = false)
{
var digits = new List<int>();
for (var i = s.Length - 1; i >= 0; i--)
{
var ordinalPosition = s[i].OrdinalPosition(allowSymbols);
digits.Add(ordinalPosition % 10);
if (ordinalPosition > 9)
digits.Add(ordinalPosition / 10);
}
return digits;
}
private static int SumDigits(this int value)
{
//return value > 9 ? ((value / 10) + (value % 10)) : value;
return ((value / 10) + (value % 10));
}
private static int ConditionalMultiplyByTwo(this int value, bool condition)
{
return condition ? value * 2 : value;
}
private static int TensComplement(this int value)
{
return (10 - (value % 10)) % 10;
}
}
将校验和验证与正则表达式模式匹配结合使用可能是有意义的.这些是我使用的正则表达式:
ISIN: ^(XS|AD|AE|AF|AG|AI|AL|AM|AO|AQ|AR|AS|AT|AU|AW|AX|AZ|BA|BB|BD|BE|BF|BG|BH|BI|BJ|BL|BM|BN|BO|BQ|BR|BS|BT|BV|BW|BY|BZ|CA|CC|CD|CF|CG|CH|CI|CK|CL|CM|CN|CO|CR|CU|CV|CW|CX|CY|CZ|DE|DJ|DK|DM|DO|DZ|EC|EE|EG|EH|ER|ES|ET|FI|FJ|FK|FM|FO|FR|GA|GB|GD|GE|GF|GG|GH|GI|GL|GM|GN|GP|GQ|GR|GS|GT|GU|GW|GY|HK|HM|HN|HR|HT|HU|ID|IE|IL|IM|IN|IO|IQ|IR|IS|IT|JE|JM|JO|JP|KE|KG|KH|KI|KM|KN|KP|KR|KW|KY|KZ|LA|LB|LC|LI|LK|LR|LS|LT|LU|LV|LY|MA|MC|MD|ME|MF|MG|MH|MK|ML|MM|MN|MO|MP|MQ|MR|MS|MT|MU|MV|MW|MX|MY|MZ|NA|NC|NE|NF|NG|NI|NL|NO|NP|NR|NU|NZ|OM|PA|PE|PF|PG|PH|PK|PL|PM|PN|PR|PS|PT|PW|PY|QA|RE|RO|RS|RU|RW|SA|SB|SC|SD|SE|SG|SH|SI|SJ|SK|SL|SM|SN|SO|SR|SS|ST|SV|SX|SY|SZ|TC|TD|TF|TG|TH|TJ|TK|TL|TM|TN|TO|TR|TT|TV|TW|TZ|UA|UG|UM|US|UY|UZ|VA|VC|VE|VG|VI|VN|VU|WF|WS|YE|YT|ZA|ZM|ZW)([0-9A-Z]{9})([0-9]{1})$
CUSIP: ^[A-Z0-9]{8}[0-9]$
http://en.wikipedia.org/wiki/International_Securities_Identification_Number
计算ISIN校验位的过程类似于CUSIP中使用的"Modulus 10 Double Add Double"技术.要计算校验位,首先通过将字母表中的序号位置加到9来将任何字母转换为数字,这样A = 10和M = 22.从最右边的数字开始,每隔一个数字乘以2.(对于CUSIP校验位,这两个步骤相反.)将得到的数字字符串(大于9的数字变为两个单独的数字)相加.从以0结尾的最小数字减去这个总和大于或等于它:这给出了校验位,也就是模10的和10的十进制补码.也就是说,得到的总和,包括检查 - 数字,是10的倍数.
他们也有一个很好的例子.
根据维基百科公布的例子，该方法是：
- 将每个字母替换为其序数（A=1、B=2 等）加上 9 ->
- 对于从最右边位置开始的偶数位置的每个数字 (
)，将其替换为其双精度的数字（两个向量条目中的两位数字）-> 
; - 验证码：
JavaScript 中一个可能的实现是：
function getVerificationCode(isin)
{
if(isin.length != 12) return null;
var v = [];
for(var i = isin.length-2; i >= 0; i--)
{
var c = isin.charAt(i);
if(isNaN(c)) //Not a digit
{
var letterCode = isin.charCodeAt(i)-55; //Char ordinal + 9
v.push(letterCode % 10);
if(letterCode > 9)
v.push(Math.floor(letterCode/10));
}
else
v.push(Number(c));
}
var sum = 0;
var l = v.length;
for(var i = 0; i < l; i++)
if(i % 2 == 0)
{
var d = v[i]*2;
sum += Math.floor(d/10);
sum += d % 10;
}
else
sum += v[i];
return 10 - (sum % 10);
}
编辑： 包括@queso 更新：
function getVerificationCode(isin) {
if (isin.length != 12) return false;
var v = [];
for (var i = isin.length - 2; i >= 0; i--) {
var c = isin.charAt(i);
if (isNaN(c)) { //not a digit
var letterCode = isin.charCodeAt(i) - 55; //Char ordinal + 9
v.push(letterCode % 10);
if (letterCode > 9) {
v.push(Math.floor(letterCode / 10));
}
} else {
v.push(Number(c));
}
}
var sum = 0;
var l = v.length;
for (var i = 0; i < l; i++) {
if (i % 2 == 0) {
var d = v[i] * 2;
sum += Math.floor(d / 10);
sum += d % 10;
} else {
sum += v[i];
}
}
return (10 - (sum % 10)) % 10
}