function for finding substring in c++stl code example

Example 1: c++ string contains

if (string1.find(string2) != std::string::npos) {
    std::cout << "found!" << '\n';
}

Example 2: string .find in c++

std::string t = "Banana Republic";
std::string s = "nana";

std::string::size_type i = t.find(s);

if (i != std::string::npos)
   t.erase(i, s.length());