(invalid_argument) Listing gives the hex2Dec(const string& h exString) function that r...

(invalid_argument) Listing gives the hex2Dec(const string& h exString) function that returns a decimal number from a hex string. Implement the hex2Dec func­tion to throw a invalid_argument exception if the string is not a hex string. Write a test program that prompts the user to enter a hex number as a string and display the number in decimal.

LISTING Hex2Dec.cpp