add a numbering to each file

[jagl]

My problem is simple but I don't see the solution I created a csv file with the date and time which will be saved in a folder my problem I just want to add a numbering to each file by exp:
when i click in the button for the first time, file name will be: Tab1_2021_07_07_07_33_55
2nd time will be: Tab2_2021_07_07_07_33_55
3rd time will be : Tab3_2021_07_07_07_33_55
code:
QString filenameTab = QDateTime :: currentDateTime () .toString (QString ("'% 1 / Tab_'yyyy_MM_dd' _ 'hh_mm'.csv"). Arg (folder));

[Pl45m4]

@jagl

QString date = QDateTime::currentDateTime().toString("yyyy_MM_dd_hh_mm");
QString folderStr = QString("Tab%1_").arg(folder);

QString filenameTab = folderStr + date + ".csv";

Then just increase the folder int counter every time you click your button.

[jagl]

@Pl45m4 thanks for your reply bu i have this error :device not open

[Pl45m4]

@jagl

That error does not come from your string :)
How do you open your file?

[jagl]

@Pl45m4
QString date = QDateTime::currentDateTime().toString("yyyy_MM_dd_hh_mm");
QString folderStr = QString("Tab%1_").arg(dossier);
QString filename = folderStr + date + ".csv";
QFile file(filename);
if(!file.open(QIODevice::WriteOnly | QIODevice:: Text)) {

//code
}

[jsulm]

@jagl said in add a numbering to each file:

file.open

So, what does open() return?
And how does filename look like?

[jagl]

@jsulm
QIODevice::write (QFile, "Tab/root/Desktop/23_2021_07_07_08_40.csv"): device not open
what does filename look like means ?

[jsulm]

@jagl said in add a numbering to each file:

what does filename look like means ?

It means: what is the content of filename variable?
Also, can you please answer this question (asked before already): what does open() return?
"device not open" means that file was NOT opened.

[Pl45m4]

@jagl said in add a numbering to each file:

Tab/root/Desktop/

The content of your dossier variable is not only "Tab" but "Tab/root/Desktop/".

Where shoudl your file really be after you create it?
Is Tab/root/Desktop/ the file path you want?

In your initial post you said, you want a filename like Tab1_2021_07_07_07_33_55, where the "1" in "Tab1" is a variable.

[jagl]

@Pl45m4 yes i want it to be variable thats my question
@jsulm
the content of filename variable:
it is a csv file which contains 4 columns the variables are of type float

[jsulm]

@jagl Could you please read more carefully what others write?
I did not ask you what is inside the file, I asked you how the file path you are trying to use looks like! So, QFile file(filename); what is the value of filename?
And now I ask for the third (and last) time: what does open() return?

[Pl45m4]

@jagl said in add a numbering to each file:

yes i want it to be variable thats my question

I understood that, but what is your desired location for this file? Do you have a folder named "Tab"?

My solution writes a file named "Tab[i]_2021_07_07_07_33_55" to your current QDir location.

• https://doc.qt.io/qt-5/qdir.html#currentPath

If you wish another destination, you need to specify a valid path, which Tab/root/Desktop/ most likely isn't.
Do you want something like root/Desktop/Tab/Tab1_2021_07_07_07_33_55.csv?

@jagl said in add a numbering to each file:

i have this error :device not open

@jsulm This comes from file.open, doesn't it? Or rather this error occures because open returned most likely false.

[jsulm]

@Pl45m4 said in add a numbering to each file:

doesn't it?

I would say it comes from a write attempt:

QIODevice::write (QFile, "Tab/root/Desktop/23_2021_07_07_08_40.csv"): device not open

[Pl45m4]

@jsulm said in add a numbering to each file:

I would say it comes from a write attempt:

Ah, yes I see, because the path is no valid writeable location. @jagl messed up the path with the variable.

[JonB]

@jagl
If I copy and paste your code you have

if(!file.open(QIODevice::WriteOnly | QIODevice:: Text)) {

//code
}

If you truly test ! file.open() then //code is in the case where it does not open correctly.