lst-0004-book.cpp
// https://godbolt.org/z/1zfo7fPcs
#include <iostream>
#include <string>
#include <string_view>
void show_middle(std::string_view msg) { // string_view is a good parameter
auto middle = msg.substr(2, msg.size()-4); // substr returns string_view
std::cout << middle << "\n";
}
int main() {
using namespace std::literals;
const std::string aaa = "##Some text##"s;
show_middle(aaa); // conversion to string_view
auto bbb = "++More text++"sv; // string_view as literal
show_middle(bbb);
}