how to know if a string is in another string c++ code example

Example 1: c++ string contains

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

Example 2: find substring in string c++

std::string parentstring = "Hello Agnosticdev, I love Tutorials";
std::string substring = "Agnosticdev";
auto index = parentstring.find(substring);