QFile::copy static function not copying file

Question

I want to copy a text file with QFile with this code:

void MainWindow::on_pushButton_4_clicked()
{
    QFile::copy("C:/p/text.txt", "C:/p/text1.txt");
}

I get no errors when I build it, but when I run the program, nothing happens.

Here's the complete source code:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QfileDialog>
#include <QFile>

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

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

int currentIndex = 0;

void MainWindow::on_pushButton_2_clicked()
{
    ui->lineEdit->setText(QFileDialog::getExistingDirectory());
}

void MainWindow::on_pushButton_clicked()
{
    currentIndex ++;
    ui->stackedWidget->setCurrentIndex(currentIndex);
}

void MainWindow::on_pushButton_3_clicked()
{
    currentIndex --;
    if(currentIndex < 0)
    {
        currentIndex ++;
    }
    ui->stackedWidget->setCurrentIndex(currentIndex);
}

void MainWindow::on_pushButton_4_clicked()
{
    QFile::copy("C:/p/text.txt", "C:/p/text1.txt");
}

What could cause this strange behaviour?

"Returns true if successful; otherwise returns false.", what do you have ? Also, "If a file with the same name already exists, copy() returns false". We need more information to help you. — Martin, Jan 01 '15 at 23:39
Check that you have the permissions to modify C:\p and that the source file exists and you have permission to read. — Luca Carlon, Jan 01 '15 at 23:44
it returns false. in the choosen directory, only the file i want to copy exists. — hardc0der, Jan 01 '15 at 23:50
@hardc0der Are you calling the function (just to make sure)? — nbro, Jan 01 '15 at 23:57
I've noticed same problem and it seems that implementation of copy() is not good. It somehow think you have no enough permission to copy even if you do. — Predrag Manojlovic, Jan 02 '15 at 00:02
Can you write in that dir from your code? Can you copy the file with other procedures in your code? http://stackoverflow.com/questions/10195343/copy-a-file-in-an-sane-safe-and-efficient-way — Luca Carlon, Jan 02 '15 at 00:06
@hardc0der Unfortunately i haven't found quality way to do it. I'll proposal a solution which works sometimes but is far from quality. — Predrag Manojlovic, Jan 02 '15 at 00:07
@hardc0der Are you sure that `on_pushButton_4_clicked` is really the *slot/listener* for a button (click) in your application? Do you have 4 buttons in your application? — nbro, Jan 02 '15 at 00:15

score 0 · Answer 1 · answered Jan 02 '15 at 00:11

0

I've noticed same problem and it seems that implementation of copy() is not good. It somehow think you have no enough permission to copy even if you do have. Some Windows permission conflict.

There is no good workaround but you might try to copy file by redoing whole process (it works sometimes):

Open source file for reading
Open (create) destination file for writing.
copy all data from first file to second one.

Far from perfect but sometimes it works.

answered Jan 02 '15 at 00:11

Predrag Manojlovic

379
5
16

well ok. but is there no better way? – hardc0der Jan 02 '15 at 00:13
Yes. Use windows native API CopyFile() – Predrag Manojlovic Jan 02 '15 at 00:14
1

In, meanwhile, make sure that you DO have enough permissions which don't require elevation and that destination file doesn't exists. – Predrag Manojlovic Jan 02 '15 at 00:16

QFile::copy static function not copying file

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