QString contains fails to find comma

[NicholasSmith]

Hi guys, I reckon I'm missing something fairly simple but I'm baffled at what. I'm passing a function a QList<QString> array of a load of info pulled out of a database, then processing it down into a CSV file with some tweaks. All works well up until it hits anything with a comma in it, the issue now is my code doesn't seem to find it.

if(passedList.value(i).contains(","))
            {
                qDebug() << "replacing";
                passedList.value(i).replace(",", " ");
            }

if(passedList.value(i).contains(","))
            {
                qDebug() << "replacing";
                passedList.value(i).replace(",", " ");
            }

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That's basically what I've been using, but it never seems to be tripped, and I'm wondering if I'm using .contains wrong in that method.

Any help would be appreciated!

[Lykurg]

It does not reach the scope or is just not replaced. The later is because value returns a copy, so you need to use QList::at().

[tbscope]

Or use a QStringlist and use replaceInStrings(...)

[NicholasSmith]

Thanks for the quick responses.

Lykurg: I tried with both .value(i) and .at(i) and neither trigger when the condition is met. Unless you mean in a manner different to passedList.at(i).contains.

tbscope: that's my other option, I wasn't aware of it when I first wrote my function and it'd involve a bit of refactoring to get it changed. I'll probably go down that route when I give up trying to get the .contains working. Intellectual challenge, or working out why I'm being a bit slow!

[Lykurg]

I see no problem with your syntax. so make a debug version an look at the values:

qDebug() <<  passedList;
qDebug() << i;
qDebug() << passedList.value(i);
qDebug() << passedList.value(i).contains(",");
if(passedList.value(i).contains(","))
            {
                qDebug() << "replacing";
                passedList.value(i).replace(",", " ");
            }

qDebug() <<  passedList;
qDebug() << i;
qDebug() << passedList.value(i);
qDebug() << passedList.value(i).contains(",");
if(passedList.value(i).contains(","))
            {
                qDebug() << "replacing";
                passedList.value(i).replace(",", " ");
            }

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What does it returns?

[tbscope]

at() and value() are const
You can't directly change a list like this, try this:

#include <QtCore/QCoreApplication>
 
#include <QStringList>
#include <QDebug>
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    qDebug() << "Test replacing comma in a string list";
    qDebug() << "";
 
    QStringList list;
    list << "a, b, c" << "d, e, f";
 
    for (int c = 0; c < list.count(); ++c) {
        qDebug() << "Line" << c+1 << "=" << list.at(c);
    }
 
    qDebug() << "";
    qDebug() << "And now without a comma:";
 
    for (int c = 0; c < list.count(); ++c) {
        QString line = list.at(c);
        line.replace(',', ' ');
        list.replace(c, line);
        qDebug() << "Line" << c+1 << "=" << list.at(c);
    }
 
    return a.exec();
}

#include <QtCore/QCoreApplication>

#include <QStringList>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    qDebug() << "Test replacing comma in a string list";
    qDebug() << "";

    QStringList list;
    list << "a, b, c" << "d, e, f";

    for (int c = 0; c < list.count(); ++c) {
        qDebug() << "Line" << c+1 << "=" << list.at(c);
    }

    qDebug() << "";
    qDebug() << "And now without a comma:";

    for (int c = 0; c < list.count(); ++c) {
        QString line = list.at(c);
        line.replace(',', ' ');
        list.replace(c, line);
        qDebug() << "Line" << c+1 << "=" << list.at(c);
    }

    return a.exec();
}

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It gives this output:

Test replacing comma in a string list 
 
Line 1 = "a, b, c" 
Line 2 = "d, e, f" 
 
And now without a comma: 
Line 1 = "a  b  c" 
Line 2 = "d  e  f"

Test replacing comma in a string list 
 
Line 1 = "a, b, c" 
Line 2 = "d, e, f" 
 
And now without a comma: 
Line 1 = "a  b  c" 
Line 2 = "d  e  f"

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[NicholasSmith]

Ah hah, it is actually spotting it and triggering, it just doesn't seem to be replacing now.

[Lykurg]

at() and value() are const

Ah, I messed it up. Once again. at() is returning a const reference, but value returning a value (which is not const for the returning value, this it what I meant). I will never keep that in mind...

const T & at ( int i ) const
T value ( int i ) const

EDIT: Without a temporary QString you have to use the [] operator.

[NicholasSmith]

Thanks chaps! I decided to just go down the temporary string route, and it works perfectly now.