c++ fatal error C1001使用可变参数模板

Question

大家好。编译我的代码时我遇到了下一个错误:
fatal error C1001:编译器中发生内部错误。

当我只将一个参数传递给“exec”函数时，一切正常。但是当我传递一个以上的参数时，它会发出错误。我分别使用vs 2015和visual c++编译器。

#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
//using namespace std;

template <class T>
void param_push_(T arg, char ** param) {
  sprintf(*param, "%15.15e", arg);
}

template <class T, class... args>
void param_push_(T first, args... args, char ** param) {
  static int param_No = 0;
  sprintf(param[param_No++], "%15.15e", first);
  param_push(args..., param[param_No]);
}

template <class ... param_types>
void exec(const char * command, const param_types& ...param_values) {

  int arg_count = sizeof...(param_values);
  char ** params = new char*[arg_count];
  for (int i = 0; i < arg_count; ++i) {
    params[i] = new char[22 * sizeof(char)];
  }

  param_push_(param_values..., params); //cast parameters to (char *)  

  for (int i = 0; i < arg_count; ++i) {
    delete[] params[i];
  }
  delete[] params;

}

int main()
{
  double e_restriction = 0.55300000000000000000124124;
  double M_restriction = 5;

  exec("SELECT \"M\",e from orbital WHERE e < $1::double precision AND \"M\" < $2::double precision", e_restriction,M_restriction);

  return 0;
}

Answer 1

试试这个 - 它有效。

#include <stdio.h>
#include <iostream>

template <typename ...> struct param_push;

template <class H, class... T>
struct param_push<H,T...> {
   void operator() (H head, T... tail, char** param) {
     sprintf(param[0], "%15.15e", head);
     param_push<T...> one_less;
     one_less(tail..., &param[1]);
   }
};

template <>
struct param_push<> {
  void operator() (char** param) {
    // does nothing, no more args to sprintf
  }
};

template <class ... param_types>
void exec(const char * command, const param_types& ...param_values) {

  int arg_count = sizeof...(param_values);
  char ** params = new char*[arg_count];
  for (int i = 0; i < arg_count; ++i) {
    params[i] = new char[22 * sizeof(char)];
  }

  // param_push_(param_values..., params); //cast parameters to (char *)
  struct param_push<param_types...> functor;
  functor(param_values..., params);

  for (int i = 0; i < arg_count; ++i) {
    std::cout << params[i] << " will be deleted" << std::endl;
    delete[] params[i];
  }
  delete[] params;

}

int main()
{
  double e_restriction = 0.55300000000000000000124124;
  double M_restriction = 5;

  exec("SELECT \"M\",e from orbital WHERE e < $1::double precision AND \"M\" < $2::double precision", e_restriction,M_restriction);

  return 0;
}

_{(现在，Arty Zefirov 的家庭作业:找到使用模板结构仿函数时该技术有效的原因，以及模板函数失败的原因，并根据发现更新您的问题)}