How can you verify if a file has been successfully opened in C++?

To verify if a file has been successfully opened in C++, using the method file.is_open() is the correct approach. This function is a part of the C++ standard library, specifically within the fstream class. When a file stream object is created, this method checks the stream's status to determine if the file was opened successfully.

When using is_open(), it returns true if the file is open and ready for reading or writing. If the file cannot be opened for some reason—such as if the specified file path is incorrect or the user lacks permissions—is_open() will return false, allowing the programmer to handle this situation accordingly, such as by displaying an error message or attempting to open a different file.

The other methods mentioned do not serve this purpose. For example, there is no standard function called isReady(), and there is also no built-in method called exists() or a status check based on booleans that would reliably indicate the file's open status after attempting to open it. Thus, file.is_open() stands out as the correct and most reliable method for confirming successful file opening in C++.