[Qt-interest] Segmentation fault while converting from QString to char*

[Ioan Calin Borcoman]

I am simply using qPrintable with great success :)

Cheers,

Ionutz

On Mon, Apr 19, 2010 at 7:14 PM, Ross Driedger <ross at earz.ca> wrote:
>
> On 19-Apr-10, at 4:00 AM, qt-interest-request at trolltech.com wrote:
>
> Message: 3
> Date: Mon, 19 Apr 2010 15:10:43 +0530
> From: prashant bhutani <prashantbhutani2008 at gmail.com>
> Subject: Re: [Qt-interest] Segmentation fault while converting from
> QString to char*
> To: qt-interest at trolltech.com
> Message-ID:
> <x2wca3e66fb1004190240yed370232oe8b7014dd481ca5e at mail.gmail.com>
> Content-Type: text/plain; charset="windows-1252"
>
> Hi,
> sorry for previous one.
> On using statement, *char *cstr = qstr.toStdString.c_str();*
> i got *?qt_file_name.QString::toStdString? does not have class type*
>
> As someone has pointed out, the 'toStdString' is a function call, so it has
> to be:
> toStdString()
> Be very careful, with your const correctness:
> char *cstr = qstr.toStdString().c_str();
> should, at the very least, give you a compiler warning  c_str() returns a
> const char* and this pointer is only valid as long as the string is in
> scope.  In my experience, const correctness is a vital subject that most c++
> courses gloss over if not entirely ignore.  If you really need to make it
> into a non-const C string than you have to make a copy of it:
> const char *cstr = qstr.toStdString().c_str();
> //buffer is a valid char array that is long enough to hold the contents of
> the string
> strcpy(cstr, buffer);
> Please note that this code is NOT safe and I leave the proper error checking
> as an exercise.
> All that said, there is usually no reason to do this kind of conversion in
> c++: anything that can be done with a char array can be done with QString or
> std:;string.
> --
> "Without music to decorate it, time is just a bunch of boring production
> deadlines or dates by which bills must be paid."
> Frank Zappa
> Ross Driedger
> ross (at) earz (dot) ca
>
>
>
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