MUST BE IN C++

Binary to Octal ) Write a function that returns an octal number from a binary number. The function header is as follows: int bin20ctal (const string& binaryString) Write a test program that prompts the user to enter a binary number as a string and displays the corresponding octal value as a string (Octal to binary) Write a function that returns a binary string from an octal number. The function header is as follows: string octal2Binary(const int& octalNumber) Write a test program that prompts the user to enter an octal number, uses octal2Binary function to parse it into an equivalent binary string and displays the binary string