Answer in C++ form. Thank you.

GRAMMING EXERCISES ns 16.2-16.4 (invalid argument) Listing 6.18 gives the hex2Dec const string& hexstring) function that returns a decimal number from a hex string. Implement the hex2Dec func- tion 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. ao enas es the hin?Dec (const