How to Read UTF-8 Encoded Files in C using fopen

Learn how to read UTF-8 encoded files in C using fopen properly, without crashing or generating unreadable characters.
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How to Read UTF-8 Encoded Files in C using fopen

In programming, handling different character encodings can be tricky, especially when you're dealing with complex scripts or special characters. One common issue that developers face is reading UTF-8 encoded files accurately in C. If you've tried to read a UTF-8 encoded file in C using fopen and encountered unreadable characters or crashes, you're not alone. In this post, we will explore how to effectively read UTF-8 encoded files in C, ensure proper character handling, and output readable results.

The Problem: Characters Not Reading Correctly

Here's a common mistake that occurs when reading such files in C:

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While you might think you are correctly opening the file in UTF-8 mode, this can cause your program to crash on certain systems like Windows 11, especially if you're using Visual Studio 2022. What can be done, then, to read these files properly?

The Solution: Read UTF-8 Files Correctly

To read UTF-8 encoded files correctly in C, follow these guidelines:

1. Use Wide Character Functions

Instead of using fgets for normal characters, switch to wide character functions. This allows you to accommodate multibyte UTF-8 characters without issues. Start by setting the locale in your program:

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2. Utilize fgetws

After setting the locale, you can read wide character strings using fgetws instead of fgets. Here’s an example:

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3. Reading as Bytes

In case you want to treat the file content as bytes, you can use the following approach, which reads input character by character and outputs them:

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You can redirect input from a UTF-8 encoded file like this:

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4. Handle Character Mapping

If you need to display these characters in ASCII format or any specific representation, here's a more thorough approach. You can develop a function that maps UTF-8 characters to their ASCII equivalents for better readability.

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Conclusion

Reading UTF-8 encoded files in C requires you to be mindful about character encodings, especially when using fopen. By using wide character functions, setting locales, and understanding how to correctly handle character output, you can successfully read and display complex character sets from your files without crashing your program. So the next time you need to handle multi-language characters, keep these tips in your toolkit!