al_ustr_find_chr
int al_ustr_find_chr(const ALLEGRO_USTR *us, int start_pos, int32_t c)
Search for the encoding of code point c in us from byte offset start_pos (inclusive).
Returns the position where it is found or -1 if it is not found.
See also: al_ustr_rfind_chr
Examples: ex_utf8
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