Qt simple to read and write and file creation

. 1  　　the QFile FP; // to include the necessary header file is omitted here
 2      the QDir (the dir);
 . 3      QString path ( " ./ " ), filename ( " test.txt " );
 . 4      QDebug qdebug (QtWarningMsg);
 . 5      FP. the setFileName (path + filename);                       // specified path comprising a file name for the fp 
. 6      IF (fp.exists ())                                      // if present, is read     
. 7      {
 . 8          QString (text);
 . 9          // char * tmp = NULL; 
10          qdebug << " file exists ";
 11          qdebug << dir.current ();                           // current path is not necessarily the path imagined 
12          fp.open (QIODevice :: ReadOnly);                    // open and close should be closely related to 
13          the while (! Fp.atEnd () )
 14          {
 15              text = fp.readAll ();
 16          }
 . 17          qdebug << " file content: " << endl << text << endl;
 18 is          fp.close ();
 . 19      }
 20 is      the else                                                 // if there , by the open operation of the new file 
21      {
 22         << qdebug " file does not exist " ;
 23  
24-          fp.open (QIODevice :: ReadWrite | QIODevice :: Text);   // absence, open the file that contains the new operating 
25          fp.write ( " the I AM Writing file " );
 26          qdebug << " writing files " ;
 27          fp.close ();
 28      }

Note: The new veteran should pay attention to the opening and closing files to be paired, can not appear alone.