book: translation of ch04

Update #12

code/4/4.2.unordered.map.cpp

@@ -0,0 +1,37 @@
+//
+// 4.2.unordered.map.cpp
+// chapter 04 containers
+// modern c++ tutorial
+//
+// created by changkun at changkun.de
+// https://github.com/changkun/modern-cpp-tutorial
+//
+
+#include <iostream>
+#include <string>
+#include <unordered_map>
+#include <map>
+
+int main() {
+    // initialized in same order
+    std::unordered_map<int, std::string> u = {
+        {1, "1"},
+        {3, "3"},
+        {2, "2"}
+    };
+    std::map<int, std::string> v = {
+        {1, "1"},
+        {3, "3"},
+        {2, "2"}
+    };
+    
+    // iterates in the same way
+    std::cout << "std::unordered_map" << std::endl;
+    for( const auto & n : u)
+        std::cout << "Key:[" << n.first << "] Value:[" << n.second << "]\n";
+    
+    std::cout << std::endl;
+    std::cout << "std::map" << std::endl;
+    for( const auto & n : v)
+        std::cout << "Key:[" << n.first << "] Value:[" << n.second << "]\n";
+}