Some c++ help please, thank you!

If you use a string object and want to convert it to a c-string, what is a function used to accomplish the task? Provide a short code sample.

If you have multiple objects consider that a customer may have multiple accounts. Can you write objects to a file?

If you want to group related variables needed as a record for a bank checking account as a record, develop that data structure.

What input validation should you implement when reading information from a file from disk? Provide a code sample with an error message(s).