[c++/en] container -> vector (#2838)

* container -> vector

fixed errors:
- "vector_name" and "Vector_name" (different case) would have resulted in a compile time error, now: "my_vector"

enhancements:
- typedef for consistency
- two push_backs to show its purpose
- both iteration types now have a working execution block (both output the vector's content)
- the first "classic loop" now also shows the operator [], which therefor is removed from below
- include and for with a white spaces for readability

* removed the typedef

the `typedef` was used to show that we will be using `string` as our base for all operations, but we are free to use any other type; of course it is technically not needed and might look like a redundancy. the two `cin` also look redundant, so I changed this into one `cin` and two `push_back`s

c++.html.markdown

@@ -1001,23 +1001,23 @@ cout << get<5>(concatenated_tuple) << "\n"; // prints: 'A'
 // Vector (Dynamic array)
 // Allow us to Define the Array or list of objects at run time
 #include <vector>
-vector<Data_Type> Vector_name; // used to initialize the vector
+string val;
+vector<string> my_vector; // initialize the vector
 cin >> val;
-Vector_name.push_back(val); // will push the value of variable into array
+my_vector.push_back(val); // will push the value of 'val' into vector ("array") my_vector
+my_vector.push_back(val); // will push the value into the vector again (now having two elements)
 
-// To iterate through vector, we have 2 choices:
+// To iterate through a vector we have 2 choices:
-// Normal looping
+// Either classic looping (iterating through the vector from index 0 to its last index):
-for(int i=0; i<Vector_name.size(); i++)
+for (int i = 0; i < my_vector.size(); i++) {
-// It will iterate through the vector from index '0' till last index
+	cout << my_vector[i] << endl; // for accessing a vector's element we can use the operator []
-
+}
-// Iterator
-vector<Data_Type>::iterator it; // initialize the iterator for vector
-for(it=vector_name.begin(); it!=vector_name.end();++it)
-
-// For accessing the element of the vector
-// Operator []
-var = vector_name[index]; // Will assign value at that index to var
 
+// or using an iterator:
+vector<string>::iterator it; // initialize the iterator for vector
+for (it = my_vector.begin(); it != my_vector.end(); ++it) {
+	cout << *it  << endl;
+}
 
 // Set
 // Sets are containers that store unique elements following a specific order.