how to compare QStringList to std::string vector

Qt Enthusiast

how to compare a std::vector<string> to a QStringList

koahnig

Checkout the different conversion routines for QList and QVector There are a couple of options for conversions.

Flotisable

Though you can convert the QStringList to std::vector<QString> by using QStringList::toVector() and QVector::toStdVector.
But there seems to be no single function to compare a std::string to a QString.
So you need to write one such function.

SGaist

Hi,

What exact comparison do you have in mind ? That they have the same content in the same order ? Or that they have all values in common ?

Qt Enthusiast

@SGaist

alll values in common

aha_1980

@Qt-Enthusiast

You cannot directly compare QString and std::string as the former is Unicode UTF-16 and the latter may have one of the 8 bit encodings.

So you need to convert one of them anyway.

J.Hilk

from what the others already said, you could do something like this:

bool compareQStdString(const QString &str1, const std::string &str2){
    return (str1 == QString::fromStdString(str2));
}


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

    QList<QString> qstrings({"a","b","c","d","e","f","g"});

    std::vector<std::string>strings({"a","b","b","d","d","f","f"});

    for(int i(0); i < qstrings.size() && i < strings.size(); i++){
        qDebug() << "Strings are at index"<< i << "are equal:" << compareQStdString(qstrings.at(i), strings.at(i));
    }

    return a.exec();
}

/*Result:
Strings are at index 0 are equal: true
Strings are at index 1 are equal: true
Strings are at index 2 are equal: false
Strings are at index 3 are equal: true
Strings are at index 4 are equal: false
Strings are at index 5 are equal: true
Strings are at index 6 are equal: false
*/

It's probably not the fastest or most elegant way to do it, but it works at least.