prime.cpp

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C++ 代码 · 共 83 行

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// developed by:
//      Erwin Unruh     [e-mail]
//
template <int i>
    struct D {
        D( void * );
        operator int();
    };

template <int p, int i>
    struct is_prime {
        enum {
            prim = (p%i) && is_prime< (i>2?p:0), i-1 >::prim
        };
    };

template <int i>
    struct Prime_print {
        Prime_print<i-1> a;
        enum {
            prim = is_prime< i, i-1 >::prim
        };
        void f() {
            D<i> d = prim;
        }
    };

struct is_prime<0,0> {
    enum {
        prim = 1
    };
};
struct is_prime<0,1> {
    enum {
        prim = 1
    };
};
struct Prime_print<2> {
    enum {
        prim = 1
    };
    void f() {
        D<2> d = prim;
    }
};

void gen_primes()
{
    Prime_print<30> a;
}