Credit Card Mask

Project: Credit Card Mask

Write a function that takes a credit card number in the format "1234 5678 9012 3456" and returns a string with all but the last four digits replaced with an "X". Use a regular expression to match a group of four digits followed by a space and replace them with "XXXX ".

Output

$ swiftc CreditCardMask.swift -I . -L . -lUtils error: link command failed with exit code 1 (use -v to see invocation) ld: library not found for -lUtils clang: error: linker command failed with exit code 1 (use -v to see invocation)

Solution