Pure Programmer
Blue Matrix

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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 ".

$ g++ -std=c++17 CreditCardMask.cpp -o CreditCardMask -lfmt $ ./CreditCardMask XXXX XXXX XXXX 3456 XXXX XXXX XXXX 1929 XXXX XXXX XXXX 3902