Why is const required [C++]?
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/3066863/whats-the-difference-between-a-const-member-function-and-a-non-const-member-func">What&#39;s the difference between a const member function and a non-const member function?</a>  </p>
</blockquote>



<pre><code>    class Message
{
    public:
        Message(const char* pStr, const char* key);
        Message(const char* pStr);
        Message();

        void encryptMessage();
        void decryptMessage();

        const char* getUnMessage() const;
        const char* getEnMessage() const;

        void getMessage();
        void getKey();

        ~Message();

    private:
        char* pUnMessage;
        char* pEnMessage;
        char* pKey;
};
</code></pre>

<p>In this program, why using const? (2 different places) Please explain those 2 for me.
Thank you very much!</p>
