prepare for c++17

code/4/4.2.cpp

@@ -0,0 +1,36 @@
+//
+// 4.2.cpp
+// c++1x tutorial
+//
+// created by changkun at shiyanlou.com
+//
+// 无序容器
+
+#include <iostream>
+#include <string>
+#include <unordered_map>
+#include <map>
+
+int main() {
+    // 两组结构按同样的顺序初始化
+    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"}
+    };
+    
+    // 分别对两组结构进行遍历
+    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";
+}