Finance Library

My Finance Library contains some utilities for finance-related operations. Its purpose is to gather various common finance operations so that developers do not have to rewrite them every time.

The library can be obtained by installing the Dandago.Finance package via Nuget. Source code is available at BitBucket.

Features

  • IBAN validation
  • Credit card number validation
    • Diner’s Club / Carte Blanche
    • American Express
    • VISA
    • MasterCard
    • Discover
  • Luhn algorithm (used in credit card validation, but can be used on its own as well)

Prerequisites

Requires .NET Framework 4.0.

Example Usages

Installing Dandago.Finance

First, install Dandago.Finance. You can do this either via the NuGet GUI:

nuget-dandago.finance

..or via the NuGet Package Manager Console:

Install-Package Dandago.Finance

Then just add the following statement to be able to access the library’s classes:

using Dandago.Finance;

Validating IBANs

Just pass the IBAN number to IbanValidator.IsValidIban():


// valid IBAN
bool valid1 = IbanValidator.IsValidIban("AL47212110090000000235698741");

// invalid IBAN
bool valid2 = IbanValidator.IsValidIban("ABCDEF");

Validating Credit Cards, and Luhn Algorithm

The CreditCardValidator provides static methods to validate the various supported credit card number types:


bool validDinersClub = CreditCardValidator.IsValidDinersClub("30569309025904");

bool validAmericanExpress = CreditCardValidator.IsValidAmericanExpress("378282246310005");

bool validVisa = CreditCardValidator.IsValidVisa("4111111111111111");

bool validMasterCard = CreditCardValidator.IsValidMasterCard("5555555555554444");

bool validDiscover = CreditCardValidator.IsValidDiscover("6011111111111117");

Each of the above checks does the following:

  1. Basic checks (e.g. empty string)
  2. Structural check (based on the format of the credit card number)
  3. Luhn algorithm to verify checksum

If you want to check whether a credit card number is valid (based on the supported types), but don’t care about the card type itself, you should use CreditCardValidator.IsValidCreditCard(), which performs #1 and #3 only once, but performs #2 per card type:


bool validWhatever = CreditCardValidator.IsValidCreditCard("5555555555554444");

The Luhn algorithm is used to validate credit card number checksums. If you want to use it separately (e.g. to validate an unsupported credit card type), you can:


bool passesLuhn = LuhnAlgorithm.IsValid("5555555555554444");

Useful Links

Release History

12th July 2015 – initial release on NuGet. Includes IBAN validator and credit card validator, the latter covering five major credit cards as well as the Luhn algorithm.

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