[SOLVED] Convert Qstring to char* and back

SGaist

Hi,

To add to Dheerendra, if you really want to validate an IP address, you should rather use a regular expression.

If it comes from a user through a QLineEdit, you can also use a validator to ensure the user is only entering correct data.

saeedhardan

thanks for tips on validating ip , but this isn't the only place i need to convert qstring to char* .

[quote author="Dheerendra" date="1408982078"]Not sure what sure what you are trying to achieve. Here is simple one based on your question.

char *datachar = data.toLocal8Bit().data();

[/quote]

i tried this method , but it doen't convert right , when i do :
char* str = ip.toLocal8Bit().data(); (ip=1.1.1.1)
str isn't 1.1.1.1 , see picture value of str .

dheerendra

Are you taking about Quotes ? which are sorounding the string ? These quotes are not part of string.

Here is the output of my program.

"1.1.1.1"
1.1.1.1
"1.1.1.1"

saeedhardan

this is the output on my machine :
!http://i58.tinypic.com/j7f7d3.png(output)!

is there something wrong with my qt ? i dont understand im new to qt so sorry if its a silly mistake

dheerendra

which platform ?

saeedhardan

windows 8.1 32bit

Qt Creator 3.1.2 Based on Qt 5.3.1 (MSVC 2010, 32 bit)

cincirin

QString::toLocal8Bit::data construct a temporary QByteArray object which will be destroyed and hence you got "bullshit" datachar contents.
QByteArray ba = data.toLocal8Bit();
char* datachar = ba.data();
In this way ba object will be destroyed on function exit

andreyc

I think qDebug() tries to be smart.
Try to use std::cout instead.

saeedhardan

[quote author="cincirin" date="1408986595"]QString::toLocal8Bit::data construct a temporary QByteArray object which will be destroyed and hence you got "bullshit" datachar contents.
QByteArray ba = data.toLocal8Bit();
char* datachar = ba.data();
In this way ba object will be destroyed on function exit[/quote]

thank you very much sir , you r right

andreyc

@
void barStd()
{
QString ip = "1.1.1.1";
qDebug() << "ip =" << ip;
char* localdata = ip.toLocal8Bit().data();
std::cout << "std::cout char* localdata = " << localdata << std::endl;
}

void barqDebug()
{
QString ip = "1.1.1.1";
qDebug() << "ip =" << ip;
char* localdata = ip.toLocal8Bit().data();
qDebug() << "qDebug() char* localdata = " << localdata;
}
@

and output
@
ip = "1.1.1.1"
qDebug() char* localdata =
ip = "1.1.1.1"
std::cout char* localdata = 1.1.1.1
@