FILE operattion

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>
#include <QFileDialog>
#include <string>
#include <math.h>       /* cos */

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(findCliecked()));
    connect(ui->pushButton_2,SIGNAL(clicked()),this,SLOT(parseLogCliecked()));
}

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

void MainWindow::findCliecked()
{
    QStringList    fileNameList;
    QFileDialog* fd = new QFileDialog(this);
    fd->resize(240,320);
    //fd->setFixedHeight(tr("Allfile(*.*);;vplog(*.vpl)")); //?置文件??器
    fd->setViewMode(QFileDialog::List);
    if ( fd->exec() == QDialog::Accepted )
    {
        fileNameList = fd->selectedFiles();
        ui->textEdit->setText(fileNameList[0]);
    }
    else
    {
        fd->close();
    }
}

void MainWindow::parseLogCliecked()
{
    QString qfilename = ui->textEdit->toPlainText();
    if (qfilename.isEmpty())
    {
        return;
    }

    std::string filename = qfilename.toStdString();
    FILE * fp = fopen(filename.c_str(),"rb");
    FILE * wfp = NULL;
    if (fp)
    {

        int n = filename.rfind('/');
        std::string cvsfilename;
        if (n != std::string::npos)
        {
            cvsfilename = filename.substr(0,n+1);
            cvsfilename += "vp.csv";
            wfp = fopen(cvsfilename.c_str(),"wb");
            if (!wfp)
            {
                fclose(fp);
                return;
            }
            char buff[] = "Time,X,Y,Z ";
            fwrite(buff, 1, strlen(buff),wfp);
        }

        char line[1024] = {0};
        char outline[1024] = {0};

        while(fgets(line,1024,fp))
        {
            std::string strline = line;
            std::string strtime = parseLine(strline,"time:","]");
            int m = strtime.find(',');
            if (m != std::string::npos)
            {
                strtime.replace(m,1," ");
            }
            std::string strX = parseLine(strline,"X:",",");
            std::string strY = parseLine(strline,"Y:",",");
            std::string strZ = parseLine(strline,"Z:",",");
            if (!strX.empty())
            {
                sprintf(outline,"%s,%s,%s,%s ",strtime.c_str(),strX.c_str(),strY.c_str(),strZ.c_str());
                fwrite(outline,1,strlen(outline),wfp);
            }
        }
    }
    fclose(fp);
    fclose(wfp);
    QMessageBox message(QMessageBox::NoIcon, "Title", "finished.");
    message.exec();
}

std::string MainWindow::parseLine(const std::string & strline, const char* start,
                      const char* end)
{
    std::string strResutl;
    int pos = strline.find(start);
    if (pos != std::string::npos)
    {
        int pos2= strline.find(end,pos);
        if (std::string::npos != pos2)
        {
            strResutl = strline.substr(pos+2,(pos2 -(pos+2)));
        }
    }

    return strResutl;
}