adding reverse iterator code

labs/06_lists_iterators/README.md

@@ -24,14 +24,18 @@ properties clear:
 ```cpp
 std::list<int> a;
 unsigned int i;
-for ( i=1; i<10; ++i ) a.push_back( i*i );
+for ( i=1; i<10; ++i ){
+	a.push_back( i*i );
+}
 std::list<int>::reverse_iterator ri;
-for( ri = a.rbegin(); ri != a.rend(); ++ri )
+for( ri = a.rbegin(); ri != a.rend(); ++ri ){
-cout << *ri << endl;
+	std::cout << *ri << std::endl;
+}
 ```
 
-This code will print out the values 81, 64, 49, . . . , 1, in order, on separate lines. Observe the type for the
+This code will print out the values 81, 64, 49, . . . , 1, in order, on separate lines. You can also compile and run this [example program](reverse_iterator.cpp).
-reverse iterator, the use of the functions rbegin and rend to provide iterators that delimit the bounds on
+
+Observe the type for the reverse iterator, the use of the functions rbegin and rend to provide iterators that delimit the bounds on
 the reverse iterator, and the use of the ++ operator to take one step backwards through the list. It is very
 important to realize that rbegin and end are NOT the same thing! One of the challenges here will be
 determining when to stop (when you’ve reached the halfway point in the list). You may use an integer

labs/06_lists_iterators/reverse_iterator.cpp

@@ -0,0 +1,18 @@
+#include <iostream>
+#include <list>
+
+int main(){
+
+	std::list<int> a;
+	unsigned int i;
+	for ( i=1; i<10; ++i ){
+        	a.push_back( i*i );
+	}
+	
+	std::list<int>::reverse_iterator ri;
+	for( ri = a.rbegin(); ri != a.rend(); ++ri ){
+		std::cout << *ri << std::endl;
+	}
+
+	return 0;
+}