Initialize std::array without constexpr

Question

void test(const std::size_t& x) {
    std::array<std::string, x> arr;
}

When I compile the above code I get this error.

main.cpp: In function ‘void test(std::size_t&)’: main.cpp:15:24: error: ‘x’ is not a constant expression

How can I get the above code to compile?

What is the reason that you try to use std::array instead of std::vector if the size is not a compile-time constant? That is pretty much the difference in use case between the two. — user17732522
– user17732522, Commented Apr 27, 2022 at 23:33

johnmastroberti · Accepted Answer · 2022-04-28 00:10:50Z

3

Template arguments must always be constant expressions, and function parameters are never constant expressions. To make this code work, you could do as is suggested in the comments and use std::vector instead, or you could make your test function be a template and make x be a template parameter instead of a function parameter.

answered Apr 28, 2022 at 0:10

johnmastroberti

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