title: C++ header and cpp file constructor multiple error
body: <p>I am coding in C++ using Clion.</p>
  <p>I am trying to make a <code>Date.cpp</code> file and a <code>Date.h</code> file.</p>
  <p>Here is my code:</p>
  <pre class="lang-cpp prettyprint-override"><code>#include &quot;Date.h&quot;
  
  // Date constructor
  Date::Date(int year, int month, int day)
  {
      SetDate(year, month, day);
  }
  
  // Date member function
  void Date::SetDate(int year, int month, int day)
  {
      m_month = month;
      m_day = day;
      m_year = year;
  }
  </code></pre>
  <pre class="lang-cpp prettyprint-override"><code>class Date
  {
  private:
      int m_year;
      int m_month;
      int m_day;
  
  public:
      Date(int year, int month, int day);
  
      void SetDate(int year, int month, int day);
  
      int getYear() { return m_year; }
      int getMonth() { return m_month; }
      int getDay() { return m_day; }
  };
  
  // Date constructor
  Date::Date(int year, int month, int day)
  {
      SetDate(year, month, day);
  }
  
  // Date member function
  void Date::SetDate(int year, int month, int day)
  {
      m_month = month;
      m_day = day;
      m_year = year;
  }
  </code></pre>
  <p>I keep getting these errors:</p>
  <blockquote>
  <p>multiple definition of Date::Date(int, int, int)</p>
  </blockquote>
  <p>and</p>
  <blockquote>
  <p>multiple definition of Date::SetDate(int, int, int)</p>
  </blockquote>
  <p>How should I reorganize my code so it stops saying I have multiple definitions?</p>