Does opencv have a constexpr vector or matrix container

[DeepMohinman]

I would like to do something like this for example:

constexpr std::array<cv::Vec3b, 6> COLORS {
cv::Vec3b(0, 255, 0), // green
cv::Vec3b(255, 0, 0), // blue
cv::Vec3b(0, 0, 255), // red
cv::Vec3b(0, 255, 255), // yellow
cv::Vec3b(255, 0, 255), // magenta
cv::Vec3b(255, 255, 0) // cyan
}
However, cv::Vec3b cannot be made constexpr, is there support for constexpr containers in opencv? Or another way around this?

Compiler error:

error: the type ‘const std::vector<cv::Vec<unsigned char, 3> >’ of ‘constexpr’ variable ‘COLORS’ is not literal
};

[George P]

You know, dude, it might be helpful to not copy'n'paste the same topic already posted elsewhere:
https://stackoverflow.com/questions/72429204/does-opencv-have-a-constexpr-vector-or-matrix-container
(there are other sites spammed with this question)

Maybe try asking this question in an opencv forum where people who know ALL about opencv might know?

[coder777]

Maybe not opencv is the culprit. The constexpr of std::vector constructor depends on the C++ Version. See:

https://en.cppreference.com/w/cpp/container/vector/vector

There might also be a difference between c array and std::array.

So whether the compiler accepts constexpr or not depends on the compiler and settings.

[seeplus]

const std::vector<cv::Vec<unsigned char, 3> >

As current, std::vector can't be used with constexpr initialisation outside of a constexpr function as any dynamic memory used is only valid within the constexpr function.