Write a c++ function that gives two option for login and signup. In case for signup the user will be given 6 random digits they must save for logging in later on and then it should proceed to login window. These random digits should be saved in a file through file handling. The user shall enter these digits correctly and it should be checked from the file digits were stored in. If it is correct the program shall continue otherwise it should give error and let the user try again. Use library for this.