cleanup some warnings

examples/btree.cc

@@ -2,29 +2,45 @@
 #include <string>
 #include <parallel_hashmap/btree.h>
 
-using phmap::btree_map;
-using phmap::btree_set;
-
 int main()
 { 
-    btree_map<std::string, int> persons = 
+    // initialise map with some values using an initializer_list
+    phmap::btree_map<std::string, int> map = 
         { { "John", 35 },
           { "Jane", 32 },
           { "Joe",  30 },
         };
 
-    for (auto& p: persons)
-        std::cout << p.first <<  " (" << p.second << ")" << '\n';
+    // add a couple more values using operator[]()
+    map["lucy"]  = 18;
+    map["Andre"] = 20;
 
-    // Create a btree_set of three floats (that map to strings)
-    using X = std::tuple<float, std::string>;
-    btree_set<X> email;
- 
-    // Iterate and print keys and values 
-    for (int i=0; i<10; ++i)
-        email.insert(X((float)i, "aha"));
+    map.insert(std::make_pair("Alex", 16));
+    map.emplace("Emily", 18); // emplace uses pair template constructor
     
-    for (auto& e: email)
-        std::cout << std::get<0>(e) << ", " << std::get<1>(e) << '\n';
-            return 0;
+    for (auto& p: map)
+        std::cout << p.first <<  ", " << p.second << '\n';
+
+    phmap::btree_map<int, std::string> map2;
+
+    map2.emplace(std::piecewise_construct, std::forward_as_tuple(0), std::forward_as_tuple(10, 'c'));
+    map2.try_emplace(1, 10, 'a'); // phmap::btree_map supports c++17 API
+
+    for (auto& p: map2)
+        std::cout << p.first <<  ", " << p.second << '\n';
+
+    // create a btree_set of tuples
+    using X = std::tuple<float, std::string>;
+    phmap::btree_set<X> set;
+ 
+    for (int i=0; i<10; ++i)
+        set.insert(X((float)i, std::to_string(i)));
+    set.emplace(15.0f, "15");
+
+    set.erase(X(1.0f, "1"));
+    
+    for (auto& e: set)
+        std::cout << std::get<0>(e) << ", \"" << std::get<1>(e) << "\" \n";
+
+    return 0;
 }