Implement I/O Methods

- [ ] Write data to a file.
- [ ] Read data from a file.
- [ ] Allow reading from input stream.
- [ ] Allow writing to an output stream.

The issue lists four I/O tasks: file write, file read, input stream reading, and output stream writing. Look for existing C++ programs in the repository to understand the project's structure and coding style. Start by implementing basic file I/O using fstream or similar C++ libraries, then extend to handle standard input/output streams. Test each method with simple data to verify functionality.

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