how to match a substring in c++ code example

Example 1: c++ check if string contains substring

string str ("There are two needles in this haystack.");
string str2 ("needle");

if (str.find(str2) != string::npos) {
//.. found.
}

Example 2: find substring in string c++

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