Set an array from array function in C++

Question

Is it possible to do something in C++ like:

uint8_t[] getSth() {
    uint8_t a[2] = {5, 2};
    return a;
}

uint8_t b[] = getSth();

No, return a will lead to undefined behavior, and uint8_t b[] = getSth() won't even compile. — barak manos
– barak manos, Commented Aug 6, 2016 at 9:32

Sergey Kalinichenko · Accepted Answer · 2016-08-06 09:38:04Z

3

No, not like that: built-in arrays decay to pointers on return, so you would end up with multiple errors and a hanging pointer.

C++ offers several solutions, though:

If the size of bis known at compile time, use std::array<uint8_t,2> as your return type, and as the type of b.
If the size of b is not known at compile time (e.g. getSth is in a different library) use std::vector<uint8_t>
If the size of bis known at compile time, and you are restricted on the library functions that you are allowed to use, you can wrap your array in a struct or a class. This is the most indirect way of doing it, so I would prefer 1 or 2 instead.

std::array<uint8_t,2> getSth() {
    std::array<uint8_t,2> a = {5, 2};
    return a;
}

std::array<uint8_t,2> b = getSth();

answered Aug 6, 2016 at 9:38

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