textbox - Inconsistencies in caret position, string length and matches index in C# -

i trying selected word in scintilla textbox using regex, , noticing inconsistencies between reported string length, matches index , caret position or start of selection:

private keyvaluepair<int, string> get_current_word() {     int cur_pos = scin_txt.selection.start;     keyvaluepair<int, string> kvp_word = new keyvaluepair<int, string>(0, "");     matchcollection words = regex.matches(scin_txt.text, @"\b(?<word>\w+)\b");     foreach (match word in words)     {         int start = word.index;         int end = start + word.length;         if (start <= cur_pos && cur_pos <= end)         {             kvp_word = new keyvaluepair<int,string>(start, word.value);             break;         }     }     return kvp_word; } 

in short, splitting string in words , using matches indexes see if caret contained within word.

unfortunately, numbers don't seem match properly:

scin_txt contains string:

"le clic droit été désactivé pour cette image. j"

this string 49 characters long, textlength property returns 53 , selection.start (or caret.position, same result) property returns 52. caret @ last position in string , there (to knowledge) no spaces or invisible characters after letter "j".

meanwhile regex match indexes , length seem correct.

is bug or there don't understand how lengths , selection indexes computed? there workaround find word containing caret?

the scintilla apis badly named. text property returns bytes, rather text, , textlength gives number of bytes, not number of characters.

presumably, using utf-8 mode, "text" acually:

le clic droit \xc3\xa9t\xc3\xa9 d\xc3\xa9sactiv\xc3\xa9 pour cette image. j

which 53 bytes long.

edit:

if want find position of start/end of word, there's sci_wordstartposition / sci_wordendposition messages. caret positioning, there's sci_positionbefore / sci_positionafter messages, take account current code-page. (presumably these messages have functional equivalents in api of particular scintilla binding using - or perhaps generic sendmessage function accessing them).