loop through characters in string c++ code example

Example 1: loop through char in string c++

std::string s("Hello world");

for (char & c : s)
{
    std::cout << "One character: " << c << "\n";
    c = '*';
}

Example 2: c++ read each char of string

std::string str = ???;
for(std::string::iterator it = str.begin(); it != str.end(); ++it) {
    do_things_with(*it);
}