How to resolve the algorithm Validate International Securities Identification Number step by step in the Nim programming language

Published on 12 May 2024 09:40 PM
#Nim

How to resolve the algorithm Validate International Securities Identification Number step by step in the Nim programming language

Table of Contents

Problem Statement

An International Securities Identification Number (ISIN) is a unique international identifier for a financial security such as a stock or bond.

Write a function or program that takes a string as input, and checks whether it is a valid ISIN. It is only valid if it has the correct format,   and   the embedded checksum is correct. Demonstrate that your code passes the test-cases listed below.

The format of an ISIN is as follows:

For this task, you may assume that any 2-character alphabetic sequence is a valid country code. The checksum can be validated as follows:

(The comments are just informational.   Your function should simply return a Boolean result.   See #Raku for a reference solution.)

Related task:

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Validate International Securities Identification Number step by step in the Nim programming language

Source code in the nim programming language

import strformat

const
  DigitRange = '0'..'9'
  UpperCaseRange = 'A'..'Z'

type ISINError = object of ValueError


proc luhn(s: string): bool =
  const m = [0, 2, 4, 6, 8, 1, 3, 5, 7, 9]
  var sum = 0
  var odd = true
  for i in countdown(s.high, 0):
    let digit = ord(s[i]) - ord('0')
    sum += (if odd: digit else: m[digit])
    odd = not odd
  result = sum mod 10 == 0


proc validateISIN(s: string) =
  if s.len != 12:
    raise newException(ISINError, "wrong length")
  if s[0] notin UpperCaseRange or s[1] notin UpperCaseRange:
    raise newException(ISINError, "wrong country code")
  if s[11] notin DigitRange:
    raise newException(ISINError, "wrong checksum character")
  var t: string
  for ch in s:
    case ch
    of '0'..'9': t.add ch
    of 'A'..'Z': t.addInt ord(ch) - ord('A') + 10
    else: raise newException(ISINError, "invalid characters in code")
  if not t.luhn():
    raise newException(ISINError, "checksum error")


when isMainModule:

  for isin in ["US0378331005", "US0373831005", "U50378331005",
               "US03378331005", "AU0000XVGZA3", "AU0000VXGZA3", "FR0000988040"]:
    try:
      isin.validateISIN()
      echo &"{isin} is valid."
    except ISINError:
      echo &"{isin} is not valid: {getCurrentExceptionMsg()}."

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