c++ - English and Greek UTF characters difference -

i have defined same char array english , greek characters.

char mytext[]="ΗΤΙΑ ΗΤΙΑΑΑ ΛΟΥΛΟΥΔΙΑΣΜΕΝΗ!!!1234567890"; //  char mytext[]="htia htiaaa louloudiasmenh!!!1234567890"; 

when print length strlen(mytext);of char array first 1 has greek utf8 characters has length of 63 characters second has 39. why happened? can fix or proper question how syntax greek unicode greek character program understand them correctly?

i send char array led matrix , message not display on screen when chars english. seems greek characters or non-ascii characters bigger 1 byte.

i have switch function check characters , returns appropriate byte array each letter.i have set default case of switch character ! instead of getting htia htia !h!t!i!a!. switch understands greek character more 1 byte , returns first default case witch ! , correct character.

also when try print text error on serial monitor(the characters not display correctly).

since utf-8 characters can have multiple bytes, , strlen counts number of bytes until first null character, strlen overcount length of utf-8 strings. 1 solution use mbstowcs() convert string wide character string, wcslen() length of wide-character string.

p.s. here demonstration of effect mentioned in question.