how to distinguish string inside "" and not in c++ code example

Example 1: c++ contains

if (s1.find(s2) != 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);