Can String Literals be Passed as Non-Type Template Arguments?

Passing String Literals to Non-Type Class Template Parameters

Question:

Can a string literal be passed as a non-type argument to a class template, such as in a declaration like my_class<"string">?

Answer:

While directly passing string literals as non-type template arguments is not possible, there is a solution that closely approximates it.

You can utilize a non-type template parameter of type const char* and pass it a const char[] variable with static linkage. This approach shares similarities with passing string literals directly.

Here's a compilable example:

#include <iostream>

template<const char *str>
struct cts {
    void p() { std::cout << str; }
};

static const char teststr[] = "Hello world!";

int main() {
    cts<teststr> o;
    o.p();
}

The above code declares a class template cts with a non-type template parameter str that takes a constant character pointer. The variable teststr, defined with static linkage, holds the string literal and is passed to the template instantiation.

This method is a viable alternative to directly passing string literals as non-type template arguments.

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