add Chapter01 examples

Chapter01/rtti.cpp

@@ -0,0 +1,29 @@
+#include <cstdio>
+
+struct Base {
+  virtual void print() { 
+      printf("Base\r\n"); 
+  }
+};
+
+struct Derived : public Base {
+  void print() override { 
+      printf("Derived\r\n"); 
+  }
+};
+
+void printer(Base &base) { 
+    base.print(); 
+
+    if(Derived *derived = dynamic_cast<Derived*>(&base); derived!=nullptr) {
+        printf("We found Base using RTTI!\r\n");
+    }
+}
+
+int main() {
+  Base base;
+  Derived derived;
+  printer(base);
+  printer(derived);
+  return 0;
+}