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  1. #include <iostream>
  2. #include <string>
  3. #include <vector>
  4.  
  5. #define IN == in
  6.  
  7. template<typename T>
  8. struct vec_val
  9. {
  10.  std::vector<T> vec;
  11. };
  12.  
  13.  template<typename T>
  14.  void add_strings(T vec){}
  15.  
  16.  template<typename T, typename... Args>
  17.  void add_strings(std::vector<T> &vec, T value, Args... args) {
  18.  	vec.push_back(value);
  19.  	add_strings(vec, args...);
  20.  }
  21.  
  22.  template<typename... Args>
  23.  void add_strings(std::vector<std::string> &vec, char const*const value_ptr, Args... args) {
  24.  	vec.push_back(std::string(value_ptr));
  25.  	add_strings(vec, args...);
  26.  }	
  27.  
  28.  template<typename... Args>
  29.  vec_val<std::string> in(char const*const value_ptr, Args... args) { 
  30.  	vec_val<std::string> vec_val_inst;
  31.  	add_strings(vec_val_inst.vec, value_ptr, args...);
  32.  	return vec_val_inst;
  33.  } 
  34.  
  35.  template<typename T, typename... Args>
  36.  vec_val<T> in(T value, Args... args) { 
  37.  	vec_val<T> vec_val_inst;
  38.  	add_strings(vec_val_inst.vec, value, args...);
  39.  	return vec_val_inst;
  40.  }
  41.  
  42. template<typename T>
  43. bool operator==(T const& str, vec_val<T> const& val) {
  44. 	for(auto &i : val.vec) 
  45. 	{
  46.  		if(i == str)
  47.  			return true;
  48.  	}
  49.  	return false;	
  50. }
  51. // -----------------------------------------------------
  52.  
  53. int main(void) 
  54. {
  55. 	std::string lang, country = "GB";
  56.  
  57. 	if (country IN ("US","GB","AU")) 
  58. 	{
  59. 		lang="en";
  60. 	}
  61.  
  62. 	//if (country IN (1,2,3)) lang="hz";	// compile error - deduced conflicting types
  63.  
  64. 	int a, b = 10;
  65.  
  66. 	if (b IN (1,2,10,3)) 
  67. 	{
  68. 		lang += " +100500";
  69. 	}
  70.  
  71. 	std::cout << "lang = " << lang << std::endl;
  72.  
  73. 	return 0;
  74. }
  75.  
Success #stdin #stdout 0s 3464KB
comments (?)
stdin 
Standard input is empty
stdout 
lang = en +100500
https://ideone.com/RUuyy7
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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