fixing the readme

labs/05_vectors/README.md

@@ -167,6 +167,26 @@ Add several test cases to test_vec.cpp to show that the function works as expect
 notation of your solution in terms of n the size of the vector, and e the number of occurences of the input
 element in the vector?
 
+*Note*: when you are in a non-member function, and you want to use the iterator, which is a member type of the Vec<T> class, you have to use the typename keyword before the Vec<T>:: scope. For example, if you want to define an iterator named *itr*, you can do it like this:
+
+```console
+typename Vec<T>::iterator itr
+```
+
+without this typename keyword, if you define the iterator *itr* like this:
+
+```console
+Vec<T>::iterator itr
+```
+
+you will get a compiler error saying:
+
+```console
+error: need ‘typename’ before ‘Vec<T>::iterator’ because ‘Vec<T>’ is a dependent scope
+```
+
+And the reason that this keyword typename is needed, is because without it, the compiler would think that Vec&lt;T&gt;::iterator is a member variable of the Vec&lt;T&gt; class, but this *typename* explicitly tells the compiler that Vec&lt;T&gt;::iterator is a type, rather than a member variable.
+
 **To complete this checkpoint**, show a TA your debugged solution for remove_matching_elements and
 be prepared to discuss the order notation of the function.
 
@@ -174,8 +194,8 @@ be prepared to discuss the order notation of the function.
 *estimate: TBD*
 
 Add a print member function to Vec to aid in debugging. (Note, neither remove_matching_elements nor
-print are not part of the STL standard for vector). You should print the current information stored in the
-variables m_alloc, m_size, and m_data. Use the print function to confirm your remove_matching_elements
+print are part of the STL standard for vector). You should print the current information stored in the
+variables capacity, m_size, and m_data. Use the print function to confirm your remove_matching_elements
 function is debugged. Also, write a test case that calls push_back many, many times (hint, use a for loop!)
 and observe how infrequently re-allocation of the m_data array is necessary.
 To verify your code does not contain memory errors or memory leaks, use Valgrind and/or Dr. Memory on