QVector of QPair<int, QString> does not sort the elements C++

MEsc

Hello,
I have a Problem. I want to sort by first Element of QPair in a QVector.
Look at the code.

Before sort:
5 dog
1 cat
3 mouse
6 rabbit
1 bird

After sort it should be:
1 cat
1 bird
3 mouse
5 dog
6 rabbit

But instead nothing happend. I dont know why...

PS: safeIn() is a Function which safes values of the QVecors in a File.

QVector<QPair<int, QString>> zip(QVector<int> algorithm, QVector<QString> language) {
	QVector<QPair<int, QString>> zipped;
	
    for(int i = 0; i < language.size(); ++i)
    {
        zipped.push_back(qMakePair(algorithm[i], language[i]));
    }
	
	return zipped;
}

void unzip(QVector<QPair<int,QString>> zipped, QVector<int> algorithm, QVector<QString> language) {
    for(int i = 0; i < language.size(); i++) {
        algorithm[i] = zipped[i].first;
        language[i] = zipped[i].second;
    }
}

bool sortbyFirst(const QPair<int, QString> &a, const QPair<int, QString> &b)
{
       return a.first < b.first;
}

void sort() {
	QVector<int> algorithm = {5, 1, 3, 6, 1};
	QVector<QString> language = {dog, cat, mouse, rabbit, bird};
	
	QVector<QPair<int, QString>> zipped = zip(algorithm, language);
	
	sort(zipped.begin(), zipped.end(), sortbyFirst);
	
	unzip(zipped, algorithm, language);
	
	for(int i = 0; i < language.size(); i++) {
                safeIn(QString::number(algorithm[i]), "C:/User/Desktop/algorithm.txt");
		safeIn(language[i], "C:/User/Desktop/animals.txt");
    }
}

Christian Ehrlicher

No sort problem but a basic c(++) problem - you pass the parameters to unzip() by value instead by reference so how should the those variables be updated outside?