Qt-interest Archive, May 2007
how to read lines of file into QString lines[]
Message 1 in thread
hi,all
i use this to read lines :
QFile file("tmp.txt");
QPtrList<QString> lines;
if ( file.open( IO_ReadOnly ) ) {
QTextStream stream( &file );
QString line;
while ( !stream.atEnd() ) {
line = stream.readLine(); // line of text excluding '\n'
lines.append(&line);
}
file.close();
}
and i want to manipulate each line in lines:
for ( QStringList::Iterator it = lines.begin(); it != lines.end(); ++it )
{
if ( *it.left(1)="#")
//do something
but gcc said
error: 'class QValueListIterator<QString>' has no member named 'left'
so *it is not QString type?
how can i get each line in lines with a type QString?
regards
--
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Message 2 in thread
i think there are some problems in u code:
first no QPtrList in Qt4, and in Qt3 it called Q3PtrList. I also can't
find the key word IO_ReadOnly ,u can use QIODevice::WriteOnly instead
it .
second : use QList<QString *> instead of QPtrList<QString> and
QList<QString*>::Iterator it instead of QStringList::Iterator
thrid : call (*it)->left(1) == "#" not *it.left(1) = "#"
å 2007-05-06æç 23:03 +0800ïjiang jefixåéï
> hi,all
> i use this to read lines :
> QFile file("tmp.txt");
> QPtrList<QString> lines;
> if ( file.open( IO_ReadOnly ) ) {
> QTextStream stream( &file );
> QString line;
> while ( !stream.atEnd() ) {
> line = stream.readLine(); // line of text excluding '\n'
> lines.append(&line);
> }
> file.close();
> }
> and i want to manipulate each line in lines:
> for ( QStringList::Iterator it = lines.begin(); it != lines.end(); ++it )
> {
> if ( *it.left(1)="#")
> //do something
> but gcc said
> error: 'class QValueListIterator<QString>' has no member named 'left'
> so *it is not QString type?
> how can i get each line in lines with a type QString?
>
> regards
>
> --
> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with "unsubscribe" in the subject or the body.
> List archive and information: http://lists.trolltech.com/qt-interest/
>
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Message 3 in thread
On 06.05.07 23:25:29, sjtu wrote:
> i think there are some problems in u code:
> first no QPtrList in Qt4, and in Qt3 it called Q3PtrList. I also can't
No, Its QPtrList in Qt3 and Q3PtrList in Qt4.
> find the key word IO_ReadOnly ,u can use QIODevice::WriteOnly instead
> it .
Thats wrong, in Qt4 its QIODevice::ReadOnly, IO_ReadOnly comes from Qt3.
> second : use QList<QString *> instead of QPtrList<QString> and
> QList<QString*>::Iterator it instead of QStringList::Iterator
> thrid : call (*it)->left(1) == "#" not *it.left(1) = "#"
No, use QStringList instead of a list of pointers to QString. There's
nearly never a reason to have pointers to QStrings.
Andreas
--
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Message 4 in thread
On 06.05.07 23:03:49, jiang jefix wrote:
> hi,all
> i use this to read lines :
> QFile file("tmp.txt");
> QPtrList<QString> lines;
> if ( file.open( IO_ReadOnly ) ) {
> QTextStream stream( &file );
> QString line;
> while ( !stream.atEnd() ) {
> line = stream.readLine(); // line of text excluding '\n'
> lines.append(&line);
> }
> file.close();
> }
> and i want to manipulate each line in lines:
> for ( QStringList::Iterator it = lines.begin(); it != lines.end(); ++it )
> {
> if ( *it.left(1)="#")
> //do something
> but gcc said
> error: 'class QValueListIterator<QString>' has no member named 'left'
> so *it is not QString type?
This has nothing to do with Qt, its a plain C++ error. The .left() is
evaluated before the * in front of it, thats why what happens is that
the code tries to call QValueListIterator<QString>::left(). Just add
some parenthesis around the *it and you're done.
Also I don't think you want a QPtrList<QString>, a QStringList should be
fine.
Andreas
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Message 5 in thread
hey,it is!
thanks a lot
--
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Message 6 in thread
> -----Original Message-----
> From: Andreas Pakulat [mailto:apaku@xxxxxx]
> Sent: Sunday, May 06, 2007 8:28 AM
> To: qt-interest@xxxxxxxxxxxxx
> Subject: Re: how to read lines of file into QString lines[]
>
> On 06.05.07 23:03:49, jiang jefix wrote:
> > hi,all
> > i use this to read lines :
> > QFile file("tmp.txt");
> > QPtrList<QString> lines;
> > if ( file.open( IO_ReadOnly ) ) {
> > QTextStream stream( &file );
> > QString line;
> > while ( !stream.atEnd() ) {
> > line = stream.readLine(); // line of text
> excluding '\n'
> > lines.append(&line);
> > }
> > file.close();
> > }
> > and i want to manipulate each line in lines:
> > for ( QStringList::Iterator it = lines.begin(); it != lines.end();
++it
> )
> > {
> > if ( *it.left(1)="#")
> > //do something
> > but gcc said
> > error: 'class QValueListIterator<QString>' has no member named
'left'
> > so *it is not QString type?
>
> This has nothing to do with Qt, its a plain C++ error. The .left() is
> evaluated before the * in front of it, thats why what happens is that
> the code tries to call QValueListIterator<QString>::left(). Just add
> some parenthesis around the *it and you're done.
>
> Also I don't think you want a QPtrList<QString>, a QStringList should
be
> fine.
>
Also... Your code wont work (Ops code... not Andreas's), since your
storing a pointer to a local variable (line in this case) each time the
while loop executes, it will overwrite the original value....
Another C++ error...
--
[ signature omitted ]
Message 7 in thread
Please don't email me directly....
It should work just fine.
Scott
> -----Original Message-----
> From: jiang jefix [mailto:jefix214@xxxxxxxxx]
> Sent: Sunday, May 06, 2007 9:02 AM
> To: Scott Aron Bloom
> Subject: Re: how to read lines of file into QString lines[]
>
> oh yes,thanks
> will this ok?
>
> QFile file("tmp.txt");
> QStringList lines;
> if ( file.open( IO_ReadOnly ) ) {
> QTextStream stream( &file );
> QString line;
> while ( !stream.atEnd() ) {
> line = stream.readLine();
> lines += line;
> }
>
>
> 2007/5/6, Scott Aron Bloom <scott@xxxxxxxxxxxx>:
> > > -----Original Message-----
> > > From: Andreas Pakulat [mailto:apaku@xxxxxx]
> > > Sent: Sunday, May 06, 2007 8:28 AM
> > > To: qt-interest@xxxxxxxxxxxxx
> > > Subject: Re: how to read lines of file into QString lines[]
> > >
> > > On 06.05.07 23:03:49, jiang jefix wrote:
> > > > hi,all
> > > > i use this to read lines :
> > > > QFile file("tmp.txt");
> > > > QPtrList<QString> lines;
> > > > if ( file.open( IO_ReadOnly ) ) {
> > > > QTextStream stream( &file );
> > > > QString line;
> > > > while ( !stream.atEnd() ) {
> > > > line = stream.readLine(); // line of text
> > > excluding '\n'
> > > > lines.append(&line);
> > > > }
> > > > file.close();
> > > > }
> > > > and i want to manipulate each line in lines:
> > > > for ( QStringList::Iterator it = lines.begin(); it !=
lines.end();
> > ++it
> > > )
> > > > {
> > > > if ( *it.left(1)="#")
> > > > //do something
> > > > but gcc said
> > > > error: 'class QValueListIterator<QString>' has no member named
> > 'left'
> > > > so *it is not QString type?
> > >
> > > This has nothing to do with Qt, its a plain C++ error. The .left()
is
> > > evaluated before the * in front of it, thats why what happens is
that
> > > the code tries to call QValueListIterator<QString>::left(). Just
add
> > > some parenthesis around the *it and you're done.
> > >
> > > Also I don't think you want a QPtrList<QString>, a QStringList
should
> > be
> > > fine.
> > >
> > Also... Your code wont work (Ops code... not Andreas's), since your
> > storing a pointer to a local variable (line in this case) each time
the
> > while loop executes, it will overwrite the original value....
> >
> > Another C++ error...
> >
> >
> >
> > --
> > To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx
with
> "unsubscribe" in the subject or the body.
> > List archive and information:
http://lists.trolltech.com/qt-interest/
> >
> >
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