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  1. #include <iostream>
  2. #include <string>
  3. #include <vector>
  4.  
  5. template<typename T>
  6. struct vec_val
  7. {
  8.  std::vector<T> vec;
  9. };
  10.  
  11.  template<typename T>
  12.  void add_strings(T vec){}
  13.  
  14.  template<typename T, typename... Args>
  15.  void add_strings(std::vector<T> &vec, T value, Args... args) {
  16.  	vec.push_back(value);
  17.  	add_strings(vec, args...);
  18.  }
  19.  
  20.  template<typename... Args>
  21.  void add_strings(std::vector<std::string> &vec, char const*const value_ptr, Args... args) {
  22.  	vec.push_back(std::string(value_ptr));
  23.  	add_strings(vec, args...);
  24.  }	
  25.  
  26.  template<typename... Args>
  27.  vec_val<std::string> in(char const*const value_ptr, Args... args) { 
  28.  	vec_val<std::string> vec_val_inst;
  29.  	add_strings(vec_val_inst.vec, value_ptr, args...);
  30.  	return vec_val_inst;
  31.  } 
  32.  
  33.  template<typename T, typename... Args>
  34.  vec_val<T> in(T value, Args... args) { 
  35.  	vec_val<T> vec_val_inst;
  36.  	add_strings(vec_val_inst.vec, value, args...);
  37.  	return vec_val_inst;
  38.  }
  39.  
  40. template<typename T>
  41. bool operator==(T const& str, vec_val<T> const& val) {
  42. 	for(auto &i : val.vec) 
  43. 	{
  44.  		if(i == str)
  45.  			return true;
  46.  	}
  47.  	return false;	
  48. }
  49. // -----------------------------------------------------
  50.  
  51. int main(void) 
  52. {
  53. 	std::string lang, country = "GB";
  54.  
  55. 	if (country == in ("US","GB","AU")) 
  56. 	{
  57. 		lang="en";
  58. 	}
  59.  
  60. 	//if (country == in (1,2,3)) lang="hz";	// compile error - deduced conflicting types
  61.  
  62. 	int a, b = 10;
  63.  
  64. 	if (b == in (1,2,10,3)) 
  65. 	{
  66. 		lang += " +100500";
  67. 	}
  68.  
  69. 	std::cout << "lang = " << lang << std::endl;
  70.  
  71. 	return 0;
  72. }
  73.  
Success #stdin #stdout 0s 3460KB
comments (?)
stdin 
Standard input is empty
stdout 
lang = en +100500
https://ideone.com/PguQHi
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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