Qfile read / write file operation in QT

Hello everyone , I meet you again , I'm your friend, Quan Jun .

1. First, record it QString,QByteArray,char * Conversion between

(1) QString -> QByteArray

QString buf = "123";
QByteArray a = buf.toUtf8(); // chinese 
a = buf.toLocal8Bit();  // Local code 

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(2) QByteArray -> char *

char *b = a.data();

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(3) char * -> QString[ Network programming often involves ]

char *p = "abc";
QString c = QString(p);

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2.QFile Read and write files

widget.cpp Source code is as follows :

#include "widget.h"
#include "ui_widget.h"
#include<QFile>
#include<QFileDialog>

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_buttonRead_clicked()
{
    QString path = QFileDialog::getOpenFileName(this,
                                                "open",
                                                "../",
                                                "TXT(*.txt)");
    if(path.isEmpty() == false){
        // File object 
        QFile file(path);

        // Open file 
        bool isOK = file.open(QIODevice::ReadOnly);
        if(isOK == true){
#if 0
            // Reading documents , The default only recognizes UTF-8
           QByteArray array = file.readAll();// Check more help documents 
           // Show to edit area 
           ui->textEdit->setText(array);
#endif
            QByteArray array;
            while (file.atEnd() == false) {
                // Read a line 
               array +=  file.readLine();
               ui->textEdit->setText(array);
            }

        }
        file.close();
    }

}

void Widget::on_buttonSave_clicked()
{
    QString path = QFileDialog::getSaveFileName(this, "save",
                                                "../", "TXT(*.txt)");
    if (path.isEmpty() == false){
        // Create a file object 
        QFile file;
        // Associated file name 
        file.setFileName(path);
        // Open file , Just write the way 
        bool isOK = file.open(QIODevice::WriteOnly);
        if (isOK == true){
            // Get the contents of the edit area 
            QString str = ui->textEdit->toPlainText();
            //write files
            //QString -> QByteArray
           // file.write(str.toUtf8());
            //QString -> C++ string ->char*
            file.write(str.toStdString().data());
        }
    }
}

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