Qt file processing

Qt provides the QFile class for file processing

class

QTextStream class or QDataStream class-read text files

QFile class-interface for reading and writing files

QDir class-directory

#include <QFile>//继承于QFileDevice类，可以直接写#include <QFileDevice>，就不用写该头文件了
#include <QDir>

plainTextEdit——没有setTest()
textEdit——可以setTest()

function

setFileName()-set the file name
open(), close()-open/close
readLine() function-read and write a line of a text file

demo

filename is defined in the type of QString