从数组初始化QVector [英] Initialize QVector from array

问题描述

我从函数中收到一个数组作为指针，并希望从中初始化一个QVector。

I receive an array as a pointer from a function and want to initialize a QVector from that.

现在，我这样做是这样的：

For now I do it like this:

void foo(double* receivedArray, size_t size)
{
    QVector<double> vec(size);

    std::copy(receivedArray, receivedArray + size, std::begin(vec));
}

是否也有可能这样做：

void foo(double* receivedArray, size_t size)
{
    QVector<double> vec(size);

    vec.data() = receivedArray;
}

这会中断我不知道的某种Qt机制吗？ / p>

Would this break some kind of Qt mechanism that I am not aware of?

推荐答案

第一个执行不必要的工作，在填充向量之前，使用默认构造的双精度数组初始化向量。不幸的是，QVector缺少远程插入，因此您必须求助于算法：

The first one does unnecessary work, initializing the vector with default-constructed doubles before filling it. Unfortunately, QVector lacks a ranged-insertion, so you must resort to algorithms:

void foo(double* receivedArray, size_t size)
{
    QVector<double> vec;
    vec.reserve(size); // warning: size_t->int cast

    std::copy(receivedArray, receivedArray + size, std::back_inserter(vec));
}

第二个版本甚至都不能编译，因为 data （）返回 T * ，这是您不能在作业左侧放置的右值。

The second version does not even compile, as data() returns a T *, which is a rvalue that you can't put on the left side of an assignment.

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