#include <iostream>

// used as conversion
constexpr long double operator"" _deg ( long double deg )
{
    return deg * 3.14159265358979323846264L / 180;
}

// used with custom type
struct mytype
{
    unsigned long long m;
};
constexpr mytype operator"" _mytype ( unsigned long long n )
{
    return mytype{n};
}

// used for side-effects
void operator"" _print ( const char* str )
{
    std::cout << str;
}

int main(){
    double x = 90.0_deg;
    std::cout << std::fixed << x << '\n';
    mytype y = 123_mytype;
    std::cout << y.m << '\n';
    0x123ABC_print;
}