Simple Question about how to put an int to a function that requires coonst QString.

[hakermania]

QProgressbar Format can be set as follow:

progressbar->setFormat("text here");
What I want is to have some text into the setFormat(); and an integer t follow.
Specifically, I need

ui->progressbar->setFormat("Starting with " + ui->listwidget->count()+ " files");

I get error

invalid operands of types ‘const char*’ and ‘const char [7]’ to binary ‘operator+’

So, how will I do what I want?

Thx for any replies, happy new year.

[SixDegrees]

Use QStrings.

[Zlatomir]

You can use the arg(..) (http://doc.qt.nokia.com/latest/qstring.html#arg-10) function, something like this should do the trick:


ui->progressbar->setFormat(QString("Starting with %1 files").arg(ui->listwidget->count()) );

[nroberts]

QProgressbar Format can be set as follow:

progressbar->setFormat("text here");
What I want is to have some text into the setFormat(); and an integer t follow.
Specifically, I need

ui->progressbar->setFormat("Starting with " + ui->listwidget->count()+ " files");

I get error

invalid operands of types ‘const char*’ and ‘const char [7]’ to binary ‘operator+’


Correct. The + operator doesn't work on C-style strings the way you'd want (it adds the pointers when it pretends to work--you're lucky it failed to compile). Operator + does work on a lot of string classes though, such as QString or std::string.



So, how will I do what I want?
.

You could make sure both "" strings are turned into QStrings before you try the +:



QString("xxx") + y + QString("snatoheusn")


You could do the arg method shown by Zlatomir.

You could use std::string similar to how I show QString above.

You could wrap in tr() instead of QString().

You could use boost::format



std::string str = boost::str(boost::format("xxx %d xxx") % i);


There's more... What you specifically need is hard to say. It sounds rather that the .arg() method might be best for you.

[wysota]

I get error

invalid operands of types ‘const char*’ and ‘const char [7]’ to binary ‘operator+’

So, how will I do what I want?
Note that the error is a little misleading. Although it complains about character strings, the real problem is the integer you are passing somewhere in the middle.

As for the + operator, it is good to always wrap all C strings into QLatin1String. It's a bit of more work but it has some benefits for more complex applications. There is not operator+ defined for it though, so it's likely you'd get some different error then too but at least the compiler wouldn't try to add an integer to your string.

[hakermania]

Thx for your replies! :):rolleyes:

[MarekR22]

Hi. IMHO the best approach in your case is:

ui->progressbar->setFormat(tr("Starting with %n files", "", ui->listwidget->count()));

This will allow to alter translation depending on number value.
http://doc.trolltech.com/4.7/qobject.html#tr
http://doc.trolltech.com/4.7/i18n-source-translation.html