这个程序不能通信编译,说明它并不是运行在运行期,它借助编译错误信息报出'指定范围的素数',比如下面程序将会在primes<x>中x是素数的类中发生错误,看错误信息吧...

#include <cstdlib>
#include <iostream>

using namespace std;

struct true_type
{
       private:
               true_type(){};
};
struct false_type{};

template<bool,typename,typename B>
struct IfThenElse
{
       typedef B result_type;
};

template<typename A,typename B>
struct IfThenElse<true,A,B>
{
      typedef A result_type;
};

template<int d,int i = d/2 >
struct is_prime
{
      typedef typename IfThenElse<d%i==0,false_type,typename is_prime<d,i-1>::result_type>::result_type result_type;
};

template<int d>
struct is_prime<d,1>
{
      typedef true_type result_type;
};

template<int d>
struct primes
{
       typedef typename is_prime<d>::result_type result_type;
       static void show()
       {
            result_type y;
            primes<d-1>::show();
       }
};

template<>
struct primes<1>
{
       static void show(){}
};

int main(int argc, char *argv[])
{
    primes<10>::show();
    system("PAUSE");
    return EXIT_SUCCESS;
}

g++.exe -c main.cpp -o main.o -I"D:/Dev-Cpp/lib/gcc/mingw32/3.4.2/include"  -I"D:/Dev-Cpp/include/c++/3.4.2/backward"  -I"D:/Dev-Cpp/include/c++/3.4.2/mingw32"  -I"D:/Dev-Cpp/include/c++/3.4.2"  -I"D:/Dev-Cpp/include"  

main.cpp: In static member function `static void primes<d>::show() [with int d = 7]':
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 8]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 9]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 10]'
main.cpp:59:   instantiated from here
main.cpp:9: error: `true_type::true_type()' is private

main.cpp:46: error: within this context

main.cpp: In static member function `static void primes<d>::show() [with int d = 5]':
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 6]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 7]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 8]'

main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 9]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 10]'
main.cpp:59:   instantiated from here
main.cpp:9: error: `true_type::true_type()' is private
main.cpp:46: error: within this context
main.cpp: In static member function `static void primes<d>::show() [with int d = 3]':
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 4]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 5]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 6]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 7]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 8]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 9]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 10]'
main.cpp:59:   instantiated from here
main.cpp:9: error: `true_type::true_type()' is private
main.cpp:46: error: within this context

main.cpp: In static member function `static void primes<d>::show() [with int d = 2]':
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 3]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 4]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 5]'

main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 6]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 7]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 8]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 9]'
main.cpp:47:   instantiated from `static void primes<d>::show() [with int d = 10]'

main.cpp:59:   instantiated from here
main.cpp:9: error: `true_type::true_type()' is private
main.cpp:46: error: within this context

make.exe: *** [main.o] Error 1

执行结束

1994年Erwin Unruh提供了一个类似的程序。这个程序没什么用，甚至不能运行，但是我觉得很酷，因为它是编译期‘工作’的，我的电脑配置低貌似会很慢，编译起来比较慢。

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