Clean up and document project files (#4560)

docs/mkdocs/docs/examples/size.cpp

@@ -0,0 +1,29 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create JSON values
+    json j_null;
+    json j_boolean = true;
+    json j_number_integer = 17;
+    json j_number_float = 23.42;
+    json j_object = {{"one", 1}, {"two", 2}};
+    json j_object_empty(json::value_t::object);
+    json j_array = {1, 2, 4, 8, 16};
+    json j_array_empty(json::value_t::array);
+    json j_string = "Hello, world";
+
+    // call size()
+    std::cout << j_null.size() << '\n';
+    std::cout << j_boolean.size() << '\n';
+    std::cout << j_number_integer.size() << '\n';
+    std::cout << j_number_float.size() << '\n';
+    std::cout << j_object.size() << '\n';
+    std::cout << j_object_empty.size() << '\n';
+    std::cout << j_array.size() << '\n';
+    std::cout << j_array_empty.size() << '\n';
+    std::cout << j_string.size() << '\n';
+}