とりあえず、区切り入れてgetlineで一行ずつ読み込めました
vector<string> moji = {"aaaaaa", "bbbbbb", "ccccccccc"};
ofstream ofs2("mojibin.bin", std::ios_base::out | std::ios_base::binary);
for (int i = 0; i <= 2; i++) {
moji[i] += "\n";
ofs2.write(moji[i].c_str(), strlen(moji[i].c_str()));
}

ifstream ifs2("mojibin.bin", std::ios_base::out | std::ios_base::binary);
string temp;
int i = 0;
while (getline(ifs2, temp, '\n')) {
cout << "(" << i << ")" << temp << " ";
i++;
}
これでまたvector<string>に入れたらいいか
c++はＨＳＰとかと違って難しいですね