ranged based for:

std::array<std::string, 3> strarr = {"ram", "mohan", "sita"};
for(const std::string& str : strarr) {
  listbox.items.add(str);
}

pre c++11

std::string strarr[] = {"ram", "mohan", "sita"};
for(int i = 0; i < 3; ++i) {
  listbox.items.add(strarr[i]);
}

or

std::string strarr[] = {"ram", "mohan", "sita"};
std::vector<std::string> strvec(strarr, strarr + 3);
std::vector<std::string>::iterator itr = strvec.begin();
while(itr != strvec.end()) {
  listbox.items.add(*itr);
  ++itr;
}

Using Boost:

boost::array<std::string, 3> strarr = {"ram", "mohan", "sita"};
BOOST_FOREACH(std::string & str, strarr) {
  listbox.items.add(str);
}