QFile讀文件+寫文件+各種字符類型間的轉換

#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)
    {
        //文件對象
        QFile file(path);

        //打開文件，只讀方式
       bool isOk = file.open(QIODevice::ReadOnly);
       if(isOk = true)
       {
#if 0
           //讀文件(方式一),默認只識別UTF-8編碼
           QByteArray array =  file.readAll();
           //顯示到編輯區
           //ui->textEdit->setText(QString(array));
           ui->textEdit->setText(array);
#endif

           //方法二，一行一行讀
            QByteArray array;
            while( file.atEnd() == false)
            {
                //讀一行
               array += file.readLine();
            }
            ui->textEdit->setText(array);
       }
       //關閉文件
       file.close();
    }
}

void Widget::on_buttonWrite_clicked()
{
    QString path = QFileDialog::getSaveFileName(this,
                         "save","../","TXT(*.txt)");
    if(path.isEmpty() == false)
    {
        QFile file;//創建文件對象
        //關聯文件名字
        file.setFileName(path);

        //打開文件，只寫方式
        bool isOk = file.open(QIODevice::WriteOnly);
        if(isOk == true)
        {
            //獲取編輯區內容
            QString str = ui->textEdit->toPlainText();
            //寫文件
            //QString->QByteArray
            //file.write(str.toUtf8());//格式1

            //QString->c++ string->char *
            file.write(str.toStdString().data());//格式2

            file.write(str.toLocal8Bit());//格式3 本地平臺編碼

            //QString->QByteArray(字節數組)
            QString buf = "123";
            QByteArray a = buf.toUtf8();//中文
            a = buf.toLocal8Bit();//本地編碼

            //QByteArray->char *
            char *b = a.data();

           // char *->QString
            char *p = "abc";
            QString c = QString(p);


        }
        file.close();
    }

}