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Meta·Software Engineer·Onsite - Coding / Algorithms·Intermediate

Intermediate
May 2026

Summary

Meta SWE coding round with a basic file I/O question. Nothing flashy, but they do care about edge case handling more than you'd expect for something this simple.

Questions Asked (1)

Q1

Write a program that reads a file and prints its contents to standard output. The file may not exist, so handle that case with a proper error message. Assume plain text, newline-separated, file size under 100KB.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Seemed trivial at first and I almost rushed it.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the requirements and constraints, then outline a solution that reads the file and handles the missing file case with a clear error message. Write clean, idiomatic code with proper error handling, and discuss trade-offs such as using exceptions vs. checking file existence.

Pro tip: Demonstrate awareness of edge cases like empty files, permission errors, and large files (even though size is bounded), and mention how you would test the solution. This shows production-level thinking beyond just solving the problem.

1. Clarify requirements and constraints

Ask clarifying questions about the environment, expected error message format, and whether the file path is provided as an argument or hardcoded. Confirm that the file is plain text and under 100KB.

2. Choose an approach and language

Select a programming language you are comfortable with (e.g., Python, Java, C++). Decide between reading the entire file at once (since size is small) or streaming line by line. Consider using built-in file I/O libraries.

3. Implement error handling

Use try-catch (or equivalent) to handle the case where the file does not exist. Print a clear error message to standard error (or standard output as specified) and exit gracefully. Optionally check file existence beforehand, but prefer exception handling for atomicity.

4. Write the code and explain

Write the code on the whiteboard or in a shared editor, explaining each part. Ensure you close the file properly (use with statement in Python or try-with-resources in Java). Print the contents to standard output.

5. Test and discuss edge cases

Walk through test cases: file exists, file missing, empty file, file with special characters. Discuss potential improvements like handling other I/O errors (permission denied) and logging.

Key Points to Mention

  • Use of try-catch or equivalent for handling file not found exception
  • Proper resource management (closing file, using with/try-with-resources)
  • Choice of reading entire file vs. line-by-line (since size < 100KB, either is fine)
  • Error message should be clear and informative, possibly to stderr
  • Consideration of other exceptions like permission errors or IO errors
  • Testing strategy: unit tests or manual test cases for missing file

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.