2D QStringList

[t021]

I need to have a 2D QStringList that stores a table. I have this but it doesn't work:

QFile outfile("file.txt"); if(!outfile.open(QIODevice::WriteOnly | QIODevice::Text)) {exit(1);}
QTextStream out_stream(&outfile);

QList<QStringList> list;
list[0].append("cat");
list[1].append("dog");
list[2].append("mouse");
out_stream << list.at(0) << list.at(1) << list.at(2);

list.clear(); 
outfile.close();

I think this should be a list of three QStringLists. So why can I not output the first three entries? Thank you!

[J.Hilk]

Hi,

QList<QStringList> list; is the same as QList<QList<QString> > list;

that mean to access a QString of that struct you need 2 indices
QString s = list[indexOfList][indexOfString];

with

QList<QStringList> list;
list[0].append("cat");
list[1].append("dog");
list[2].append("mouse");

you expect list to allready have 3 QStringLists where you than append a new QString

to append a QStringList to your List
you could write the following

QList<QStringList> list;
list.append(QList<QString>{"cat"});
list.append(QList<QString>{"dog"});
list.append(QList<QString>{"mouse"});

[t021]

@J.Hilk
Than you. I see. But then the out_stream line still won't compile. I now have this:

QFile outfile("file.txt"); if(!outfile.open(QIODevice::WriteOnly | QIODevice::Text)) {exit(1);}
QTextStream out_stream(&outfile);

QList<QStringList> list;
list.append(QList<QString>{"cat"});
list.append(QList<QString>{"dog"});
list.append(QList<QString>{"mouse"});
out_stream << list[0][0];

list.clear(); 
outfile.close();

[t021]

I'd actually really like to use pointers, if possible. This is something really simple.

QStringList* stringp[3];
stringp[0]->append("cat");
QString Cat=stringp[0][0];

The first two lines should be OK. If I could only find a way to retrieve that "cat" entry (as a QString for example, as presented here) I should be good to go.

[SGaist]

Hi,

What is out_stream ?

What errors do you get ?

[jsulm]

@t021 You should avoid pointers as much as possible.
To retrieve cat do:

QStringList stringp[3];
stringp[0].append("cat");
QString Cat=stringp[0][0];

If you insist to use pointers:

QStringList* stringp[3];
stringp[0]->append("cat");
QString Cat=(*stringp[0])[0];

[J.Hilk]

@t021 there has to be an error with your outstream because, using <QDebug> I can access all QStrings of the 2D List without any problem:

QList<QStringList> list;
list.append(QList<QString>{"cat"});
list.append(QList<QString>{"dog"});
list.append(QList<QString>{"mouse"});
list.append(QList<QString>{"cat","dog","mouse"});

for(auto a : list)
        for(auto b : a)
            qDebug() << b;

Console result:

• "cat"
• "dog"
• "mouse"
• "cat"
• "dog"
• "mouse"

Show us the error msg you get.

[t021]

Thank you to all!! This version works, so the problem is solved:

QStringList stringp[3];
stringp[0].append("cat");
QString Cat=stringp[0][0];