title: Difference between std:string and std::string
body: <p>In one function of my code I found a bug. It was written <code>std:string</code> :</p>
  
  <pre><code>const std::string currentDateTime() {
      time_t     now = time(0);
      struct tm  tstruct;
      char       buf[80];
      tstruct = *localtime(&amp;now);
      //strftime(buf, sizeof(buf), "%Y-%m-%d.%X", &amp;tstruct);
      strftime(buf, sizeof(buf), "%Y%m%d%X", &amp;tstruct);
  
      std:string str = buf;
  
      str.erase(std::remove(str.begin(), str.end(), ':'), str.end());
      return str;
  }
  </code></pre>
  
  <p>The code compiles without errors. Why does it compile? What does <code>std:string</code> mean then?</p>