Updated v2_0_cpp_tutorial (markdown)

v2_0_cpp_tutorial.md

@@ -29,3 +29,46 @@ https://wandbox.org/permlink/9g8uhDsVHAW1rpwV
 
 Because some environment often has installed older-version of the `msgpack-c` in `/usr/include`. It is very confusing. So I recommend the version of `msgpack-c` that actually you include.
 
+## Packing
+
+### Single value
+
+Let's pack the small string "compact". Pack means encoding C++ types to MessagePack format data.
+Here is an example:
+
+```cpp
+#include <iostream>
+#include <sstream>
+
+#include <msgpack.hpp>
+
+// hex_dump is not a part of msgpack-c. 
+inline std::ostream& hex_dump(std::ostream& o, std::string const& v) {
+    std::ios::fmtflags f(o.flags());
+    o << std::hex;
+    for (auto c : v) {
+        o << "0x" << std::setw(2) << std::setfill('0') << (static_cast<int>(c) & 0xff) << ' ';
+    }
+    o.flags(f);
+    return o;
+}
+
+int main() {
+    std::stringstream ss;
+    msgpack::pack(ss, "compact");
+    hex_dump(std::cout, ss.str()) << std::endl;
+}
+```
+
+https://wandbox.org/permlink/c6oFGZWtYiGNF8f6
+
+You get the following output:
+
+```
+0xa7 0x63 0x6f 0x6d 0x70 0x61 0x63 0x74 
+```
+
+`A7` means 7 bytes string. And the body of the string continues.
+See https://msgpack.org/
+
+This is a string example. Other types are mapped as documented [here](v2_0_cpp_adaptor).