Write a function that returns a decimal number from a binary string. The function header is as follows: int bin2Dec(const string& binaryString) For example. binaryString 10001 is 17 (1x2^4 + 0x2^3 + 0x2^2 + 0x2^1 +1x2^0 = 17). So, bin2Dec ("10001") returns 17. b. Write a function that parses a decimal number into a binary number as a string. The function header is as follows: string dec2Bin(int value) For example. dec2Bin (17) returns string "10001". c. Write a test program that prompts the user to enter a binary or decimal number and display its equivalent value in decimal or binary