Consider the following code segment:
try :
inputFile = open("lyrics.txt", "r")
line = inputFile.readline()
print(line)
_____________________
print("Error")

What should be placed in the blank so that the program will print Error instead of crashing if an exception occurs while opening or reading from the file?

Question

Consider the following code segment:
try :
   inputFile = open("lyrics.txt", "r")
   line = inputFile.readline()
   print(line)
_____________________
   print("Error")
        
What should be placed in the blank so that the program will print Error instead of crashing if an exception occurs while opening or reading from the file?

BlackTom AI · Accepted Answer

We need to fill in a except clause so that any exception raised during opening or reading the file is caught and the program prints "Error" instead of crashing.
Option 1: except RuntimeError :
This would only catch RuntimeError exceptions. File I/O operations typically raise OSError or its subclasses, not RuntimeError, so this block would not handle most common file-related errors.
Option 2: except IndexError :
IndexError is raised when list indices (or similar) are out of range. It has no relevance to file I/O, so this clause would fail to catch actual file-access exceptions and the program would still crash if a file error occurred.
Option 3: except EnvironmentError :
EnvironmentError is an older alias that, in newer Python versions, maps to OSError. While this could catch some environmental I/O issues, it’s a broader, less explicit choice and not as precise as targeting IOError/OSError for file operations. Depending on the Python version, this may or may not behave as expected, making it a less reliable match for a typical open/read failure.
Option 4: except IOError :
Open and read operations commonly raise IOError (in Python 2) or, in Python 3, IOError is a separate alias that effectively behaves like OSError. Using except IOError : will catch the typical I/O related exceptions from open or readline calls and prevent a crash, allowing the program to proceed to execute the print("Error") line when such an exception occurs.
In summary, the most appropriate and reliably matching exception type for problems occurring during opening or reading the file is the one that targets input/output errors specifically, while the other options either address unrelated errors or rely on less precise or outdated classifications.

Fal25_CS003C_74229 Ch. 7 Pre-Quiz (Remotely Proctored)

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