Скачать или смотреть Modern C++: How to Use stringstream for Exact Pattern Matching Instead of scanf

Learn how to effectively translate `scanf` pattern matching into modern C++ using `stringstream` for reading files. Improve your object file parsing with a custom extractor.
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This video is based on the question https://stackoverflow.com/q/71325940/ asked by the user 'startresse' ( https://stackoverflow.com/u/12172419/ ) and on the answer https://stackoverflow.com/a/71326200/ provided by the user 'Jerry Coffin' ( https://stackoverflow.com/u/179910/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Modern C++: How to Use stringstream for Exact Pattern Matching Instead of scanf

When working with C++, especially when dealing with file input and parsing, many developers find themselves wanting to step away from the traditional C-style functions like scanf. This is particularly important in the context of reading complex data files, such as Wavefront OBJ files. If you've been faced with the challenge of translating scanf exact matching into a more modern C++ approach using stringstream, you're in the right place.

The Problem

You might have an existing C code like this:

[[See Video to Reveal this Text or Code Snippet]]

This code efficiently reads 3 floating-point numbers after matching the "vn" prefix, but it relies on the C standard library function. If you're transitioning to C++, you may wonder how to implement this functionality using stringstream.

The Modern C++ Approach to Pattern Matching

To achieve a similar level of pattern matching with stringstream, you'll need a custom solution. Let's break it down into manageable steps:

Custom Stream Extractor

One efficient way to improve your stringstream functionality is to implement a custom extractor that can match literals (like "vn") while reading from the stream. Here's a simple implementation:

[[See Video to Reveal this Text or Code Snippet]]

Using the Custom Extractor

You can then use this custom extractor within your existing parsing logic like so:

[[See Video to Reveal this Text or Code Snippet]]

This approach allows you to maintain the structure and functionality of the original code while leveraging modern C++ features.

Handling Other Patterns

For translating other patterns such as:

[[See Video to Reveal this Text or Code Snippet]]

You can similarly extend your custom extractor to cater to integers or other patterns as needed, ensuring you adjust for leading spaces and ensure exact matches.

Conclusion

Transitioning from scanf to stringstream combined with a custom extractor not only modernizes your code but also enhances its safety and readability. This way, you can efficiently read and parse your object files without losing the precision and control provided by scanf.

Embracing these modern techniques will make your C++ development experience more enjoyable and maintainable. Happy coding!