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  1. #include <iostream>
  2. #include <map>
  3. #include <set>
  4. #include <vector>
  5. #include <algorithm>
  6. #include <type_traits>
  7.  
  8. template <typename T>
  9. class has_find {
  10.     template <typename C> static std::true_type test( decltype(&C::find) ) ;
  11.     template <typename C> static std::false_type test(...);
  12. public:
  13. 	using type = decltype(test<T>(nullptr));
  14.     static const bool value = type();
  15. };
  16.  
  17. template <typename T>
  18. int foo( const T & t ) { return 1; }
  19.  
  20. // overload for std::vector
  21. template <class T>
  22. int foo( const std::vector< T > & vec ) { return 2; }
  23.  
  24. template <class T, class U>
  25. int foo( const std::map< T, U > & vec ) { return 3; }
  26.  
  27. template<class T>
  28. int foo(const std::basic_string<T>& str){ return 4; }
  29.  
  30. template <class T>
  31. int foo( const std::set< T > & vec ) { return 5; }
  32.  
  33. template<class C>
  34. bool contains(C const& c, typename C::value_type const& e){
  35. 	return std::find(begin(c), end(c), e) != std::end(c);
  36. }
  37.  
  38. template<template<class...> class C, class E, class ... Etc>
  39. auto contains(C<E, Etc...> const& c, E const& e) -> decltype(c.find(e), true) {
  40. 	return c.find(e) != std::end(c);
  41. }
  42.  
  43. template<class E, class ... Etc>
  44. auto contains(std::basic_string<E, Etc...> const& c, E const& e) -> bool {
  45. 	return c.find(e) != std::string::npos;
  46. }
  47.  
  48. template<class C, class E, class ... Es>
  49. auto contains(C const& s, E const & e, Es...es) -> bool {
  50. 	return contains(s, e) && contains(s, es...);
  51. }
  52.  
  53. int main() {
  54. 	std::map<int, std::string> m {{4,"test"}};
  55. 	std::vector<int> v;
  56. 	std::set<int> s {2,4,6,8};
  57. 	int i{};
  58. 	std::string str = "abcz";
  59. 	std::cout << foo(i) << foo(v) << foo(m) << foo(str);
  60. 	std::cout << contains(v, 4) << contains(m, 4) << contains(s, 2, 4, 6) << contains(str, 'z')
  61. 	<< contains(str, 'z', 'a');
  62. }
  63.  
Success #stdin #stdout 0.01s 5360KB
comments (?)
stdin 
Standard input is empty
stdout 
123401111
https://ideone.com/95FuVU
overload for map, vector, string
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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