How to perform c++ string operation on turkish language

i want to get string length of turkish string language . the string is İİÜ it return length 6 but it should return 3 . even if i get character at 0 position it return empty

if you are using std::string you might be better suited asking on a c++ forum. Also, perhaps googling first might help: https://www.google.com/search?client=firefox-b-1-d&q=c%2B%2B+turkish+strings