Can constexpr Variables Hold Strings in C ?

constexpr Variables and String Literals

In C , constexpr variables must have a literal type, meaning they cannot hold objects with non-trivial destructors. When attempting to define a constexpr std::string variable in C 11, an error is encountered due to the non-trivial destructor of std::string.

Alternative for constexpr String Literals

As of C 20, it is possible to use std::string in constexpr expressions under certain conditions. Specifically, the std::string must be destroyed by the end of constant evaluation.

Example:

constexpr std::size_t n = std::string("hello, world").size();

In this example, the std::string will be destroyed as part of the expression evaluating the size, so the code is valid.

String_View Alternative

Another option to use string-like objects in constexpr expressions is to utilize std::string_view introduced in C 17.

Example:

constexpr std::string_view sv = "hello, world";

std::string_view represents a string-like object with immutable, non-owning access to an underlying sequence of characters. It does not have a non-trivial destructor, making it suitable for use in constexpr expressions.

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