c++ check if string only contains letters code example

Example 1: how to check string contains char in c++

std::string s = "Hello";
if (s.find('e') != std::string::npos)
    cout << "Found";
else
    cout << "Not Found";

Example 2: 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.
}