C# and C++ example of identifying the bank from the card number. Only the first 8 credit card digits are needed. were about 6 banks from Canada and Estonia eliminated from the data source, then only the first 6 digits would be needed.
Visa, MasterCard, and other card networks allocate ranges of numbers to banks and institutions. Generally, the first 6 digits of the card number identify the bank issuer. Though there are some isntances of only 4 digits being needed and a few examples of 8 digits being needed.
The associations between credit card prefixes and banks is stored in a CSV file. For both the C# and C++ file, I've embedded the files into the executables as resources. I found the data source for this from the website of Steve Morse. He said that the data was once part of a Wikipedia article, but was removed. This information might be incomplete or outdated. It is only provided as an example. If you need a data source for a production environment, please look elsewhere. While this code is fine for an exmple, it is not to be relied upon for something of commercial interest.