#define PER_MILLE_SIGN "\u2030"
 
#define CODEPOINT_(x) * U ## x // Prepend char32_t prefix, get first element of string literal.
#define CODEPOINT(x) CODEPOINT_(x) // Tame catenation operator.
 
wchar_t *s1 = L"" PER_MILLE_SIGN;
char *s2 = "123 " PER_MILLE_SIGN;
constexpr char16_t c{ CODEPOINT( PER_MILLE_SIGN ) }; // Narrowing safe; CODEPOINT is constant expression.
 
#include <iostream>
 
int main() {
	switch ( 0x2030 ) {
		case c: std::cout << s2 << '\n';
	}
}
 

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