1 files changed, 89 insertions, 1 deletions
diff --git a/c++.html.markdown b/c++.html.markdown
index d03092e5..44cad665 100644
--- a/c++.html.markdown
+++ b/c++.html.markdown
@@ -149,7 +149,7 @@ namespace First {
 namespace Second {
     void foo()
     {
-        printf("This is Second::foo\n")
+        printf("This is Second::foo\n");
     }
 }
 
@@ -801,6 +801,94 @@ void doSomethingWithAFile(const std::string& filename)
 //   all automatically destroy their contents when they fall out of scope.
 // - Mutexes using lock_guard and unique_lock
 
+// containers with object keys of non-primitive values (custom classes) require
+// compare function in the object itself or as a function pointer. Primitives
+// have default comparators, but you can override it.
+class Foo {
+public:
+	int j;
+	Foo(int a) : j(a) {}
+};
+struct compareFunction {
+    bool operator()(const Foo& a, const Foo& b) const {
+        return a.j < b.j;
+    }
+};
+//this isn't allowed (although it can vary depending on compiler)
+//std::map<Foo, int> fooMap;
+std::map<Foo, int, compareFunction> fooMap;
+fooMap[Foo(1)]  = 1;
+fooMap.find(Foo(1)); //true
+
+///////////////////////////////////////
+// Lambda Expressions (C++11 and above)
+///////////////////////////////////////
+
+// lambdas are a convenient way of defining an anonymous function
+// object right at the location where it is invoked or passed as 
+// an argument to a function.
+
+// For example, consider sorting a vector of pairs using the second 
+// value of the pair
+
+vector<pair<int, int> > tester;
+tester.push_back(make_pair(3, 6));
+tester.push_back(make_pair(1, 9));
+tester.push_back(make_pair(5, 0));
+
+// Pass a lambda expression as third argument to the sort function
+// sort is from the <algorithm> header
+
+sort(tester.begin(), tester.end(), [](const pair<int, int>& lhs, const pair<int, int>& rhs) {
+        return lhs.second < rhs.second;
+    });
+
+// Notice the syntax of the lambda expression,
+// [] in the lambda is used to "capture" variables
+// The "Capture List" defines what from the outside of the lambda should be available inside the function body and how.
+// It can be either:
+//     1. a value : [x]
+//     2. a reference : [&x]
+//     3. any variable currently in scope by reference [&]
+//     4. same as 3, but by value [=]
+// Example:
+
+vector<int> dog_ids;
+// number_of_dogs = 3;
+for(int i = 0; i < 3; i++) {
+	dog_ids.push_back(i);  
+}
+
+int weight[3] = {30, 50, 10};
+
+// Say you want to sort dog_ids according to the dogs' weights
+// So dog_ids should in the end become: [2, 0, 1]
+
+// Here's where lambda expressions come in handy
+
+sort(dog_ids.begin(), dog_ids.end(), [&weight](const int &lhs, const int &rhs) {
+        return weight[lhs] < weight[rhs];
+    });
+// Note we captured "weight" by reference in the above example.
+// More on Lambdas in C++ : http://stackoverflow.com/questions/7627098/what-is-a-lambda-expression-in-c11
+
+///////////////////////////////
+// Range For (C++11 and above)
+///////////////////////////////
+
+// You can use a range for loop to iterate over a container
+int arr[] = {1, 10, 3};
+
+for(int elem: arr){
+	cout << elem << endl;
+}
+
+// You can use "auto" and not worry about the type of the elements of the container
+// For example:
+
+for(auto elem: arr) {
+	// Do something with each element of arr
+}
 
 /////////////////////
 // Fun stuff