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Unicode Foundations

Code points and scalar values UTF-8 byte sequences UTF-16 surrogate pairs Grapheme clusters Combining marks Normalization NFC Normalization NFD Replacement character U+FFFD

HTML & Web Encoding

HTML meta charset HTTP Content-Type charset URL percent-encoding Form URL encoding JSON Unicode escapes JavaScript Unicode escapes HTML character references Base64 versus text encoding

Strings & Storage

UTF-8 file reading Byte length versus character length Safe string slicing Case folding Locale-sensitive casing Emoji sequences Zero-width joiner BOM handling

Validation & Debugging

Detecting mojibake Invalid UTF-8 handling Round-trip encoding Database utf8mb4 Collation versus encoding Unicode-aware regex Normalization before comparison Security confusables

Character Encoding & Unicode / Unicode Foundations

Replacement character U+FFFD

Learn Replacement character U+FFFD in Character Encoding & Unicode with a focused explanation, a topic-specific example, and a mastery check.

12 min read • Beginner

encoding-008.txt

text

raw=b'valid\xfftext'
print(raw.decode('utf-8', errors='replace'))

What to watch

Content source & attribution

Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

Replacement character U+FFFD Mastery Check →

Normalization NFD

HTML meta charset