A simple C99 library for converting from and to UTF-8/16/32, based on plan9's libutf, but with more predictable handling of malformed UTF sequences. Everything's documented in utf.h.

Like libutf:

• runetochar(buf, rune)
• chartorune(rune, str)
• runelen(rune)
• runenlen(rune, n)
• fullrune(str, n)
• utflen(str)
• utfnlen(str, maxlen)
• utfrune(str, rune)
• utfrrune(str, rune)
• utfutf(str, substr)

Additions:

• loop_runes(i, rune, str, n, body)

      const char *foo = "tschüss";
      Rune rune;
      size_t i;
  
      loop_runes(i, rune, foo, strlen(foo), {
          printf("%zu. Rune is U+%"PRIRune"\n", i + 1, rune);
      });

• charntorune(rune, str, n)

• validrune(rune)

• utfvalid(str)

• runetochar16(buf, rune)

• runetochar32(buf, rune)

• runetowchar(buf, rune)

• char16ntorune(rune, str, n)

• char32ntorune(rune, str, n)

• wcharntorune(rune, str, n)

• utfconv(ret, rettype, str, strtype)