EOFError

EOFError is a built-in Python exception raised when the input() function encounters an end-of-file (EOF) condition on the input stream. It indicates that there is no more data to read from the user or from the source feeding input to the program. The condition typically occurs in interactive sessions when the user signals EOF (for example, pressing Ctrl-D on Unix-like systems or Ctrl-Z on Windows) or when a program reads from a file or pipe that ends before input() completes.

Causes and context: EOFError arises when input() cannot obtain a complete line of input because the underlying stream has reached its end. This can happen in scripts that read from standard input derived from a file, a pipeline, or an interactive terminal where the user signals EOF. It can also occur if a program calls input() after the input source has already been consumed or closed.

Handling and best practices: The common approach is to catch EOFError with a try/except block to allow graceful termination or a controlled fallback. For example:

try:

s = input("Enter value: ")

except EOFError:

print("No more input.")

# exit or break a loop

In loops that read until input ends, catching EOFError and breaking is a typical pattern. If you need to detect end-of-file without exceptions, prefer methods like sys.stdin.readline() or iterating over sys.stdin, which return '' (empty string) at EOF rather than raising an exception.

Relation to other concepts: EOFError is primarily associated with Python’s input() function. It is distinct from end-of-file indications provided by other I/O operations, which may return empty strings or shorter reads rather than raising exceptions.