Final answer:
When an input operation is carried out on a file in a fail state, the operation won't succeed and the state persists. To resume file operations, the fail state must be reset, usually with the clear() function in C++. Proper error checking and handling are crucial for robust applications.
Step-by-step explanation:
When an input operation is attempted on a file that is in a fail state, the operation will not be performed and the fail state will remain. This is because once a file stream enters a fail state, due to reasons such as reading past the end of the file or encountering data of a wrong format, further read attempts are halted until the fail state is cleared. In programming languages like C++, this is typically handled by using member functions such as clear() to reset the fail state before attempting further operations.
In practice, when an input operation fails, it's essential to check for this condition using the file stream status functions provided by the language, such as fail() in C++. If the checks are not done, and an attempt is made to continue reading from a file in a fail state without resetting it, it can lead to unexpected behaviors, incorrect data being processed, or even application crashes depending on how the rest of the code handles these error conditions.
Developers usually manage such error conditions by writing code that first checks if the file is open correctly and then whether each read operation is successful. For robustness, a good practice is to cater for exceptions or error states and handle them using appropriate error-handling mechanisms, ensuring that the program can either recover from the error, notify the user accordingly, or exit gracefully.