copying a std::vector to a qvector

Question

I tried copy content of one vector to a QVector using the following

std::copy(source.begin(), source.end(), dest.begin());

However the destination QVector still is empty.

Any suggestions ?

Solution 1

Look at:

std::vector<T> QVector::toStdVector () const
QVector<T> QVector::fromStdVector ( const std::vector<T> & vector ) [static]

From docs

Solution 2

If you are creating a new QVector with the contents of a std::vector you can use the following code as an example:

   std::vector<T> stdVec;
   QVector<T> qVec = QVector<T>::fromStdVector(stdVec);

Solution 3

'fromStdVector' has been explicitly marked deprecated recently. Use following code:

std::vector<...> stdVec;
// ...       
QVector<...> qVec = QVector<...>(stdVec.begin(), stdVec.end());

Solution 4

As the other answers mentioned, you should use the following method to convert a QVector to a std::vector:

std::vector<T> QVector::toStdVector() const

And the following static method to convert a std::vector to a QVector:

QVector<T> QVector::fromStdVector(const std::vector<T> & vector)

Here is an example of how to use QVector::fromStdVector (taken from here):

std::vector<double> stdvector;
stdvector.push_back(1.2);
stdvector.push_back(0.5);
stdvector.push_back(3.14);
QVector<double> vector = QVector<double>::fromStdVector(stdvector);

Don't forget to specify the type after the second QVector (it should be QVector<double>::fromStdVector(stdvector), not QVector::fromStdVector(stdvector)). Not doing so will give you an annoying compiler error.

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Comments

[Praetorian]

Use QVector::fromStdVector

[Rajeshwar]

tried that. as MyQvector.fromStdVector(MyStedVector); still the qvector is empty

[user1837009]

@Rajeshwar: because it static method, try: MyQvector = QVector::fromStdVector( MyStedVector );

[Kafka]

I really don't see why QT team has deprecated this function. it seems quite useful and more easy to write in my mind ...