Qt中的QFile读写文件操作

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1.首先记录一下QString,QByteArray,char * 之间的转换

(1) QString -> QByteArray

QString buf = "123";
QByteArray a = buf.toUtf8(); //中文
a = buf.toLocal8Bit();  //本地编码

(2) QByteArray -> char *

char *b = a.data();

(3) char * -> QString[网络编程常常涉及到]

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

2.QFile读写文件

widget.cpp源码如下:

#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){
        //文件对象
        QFile file(path);

        //打开文件
        bool isOK = file.open(QIODevice::ReadOnly);
        if(isOK == true){
#if 0
            //读文件,默认只识别UTF-8
           QByteArray array = file.readAll();//多查看帮助文档
           //显示到编辑区
           ui->textEdit->setText(array);
#endif
            QByteArray array;
            while (file.atEnd() == false) {
                //读一行
               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){
        //创建文件对象
        QFile file;
        //关联文件名字
        file.setFileName(path);
        //打开文件,只写方式
        bool isOK = file.open(QIODevice::WriteOnly);
        if (isOK == true){
            //获取编辑区内容
            QString str = ui->textEdit->toPlainText();
            //write files
            //QString -> QByteArray
           // file.write(str.toUtf8());
            //QString -> C++ string ->char*
            file.write(str.toStdString().data());
        }
    }
}