title: Expression must have class type
body: <p>I am assuming this has something to do with the pointer, but here is my code that is having the error. Obviously I am not done yet, but the error is with the keys in the code below.</p>
  
  <pre><code>bool LCR_cipher::iskeysOK()
  {
      vector&lt;char&gt; v(keys.begin(), keys.end());
      std::transform(v[0].begin(), v[0].end(), v[0].begin(), ::tolower);
  }
  </code></pre>
  
  <p>Here is the header file </p>
  
  <pre><code>class LCR_cipher
  {
  public:
      // Constructor:
      LCR_cipher(char *context_string, char *keys_string);
      // Destructor: deallocate memory that was allocated dynamically
      ~LCR_cipher();
      //check whether *keys string has valid LCR encryption value
      bool iskeysOK();
      //encrypt context string
      void encryption();
      //unencrypt context string (optional)
      void unencryption();
      //check whether the context string is encrypted or not
      bool isencrypted();
      //Retrieve CLR encryption value from *keys string
      void getkeys(int&amp; a, int&amp; c);
      // output the *context to console
      void output_context();
  private:
      char *context; //array to store context string
      char *keys; //array to store encryption keys
      bool encrypted; //whether string in *context is encrypted or not
      int context_MaxSize;
      int context_CurrentSize;
      int keys_MaxSize;
      int keys_CurrentSize;
  </code></pre>
  
  <p>}</p>
  
  <p>Where did I go wrong here?</p>