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  1.  
  2.     #include <type_traits>
  3.     #include <iostream>
  4.  
  5.  
  6.     template <typename T>
  7.     class is_int_or_float : public std::integral_constant<bool, std::is_same<T, int>::value || std::is_same<T, float>::value> {
  8.     };
  9.  
  10.  
  11.     template<typename T, typename Enable = void> //(2)
  12.     struct Helper {
  13.         static void go(const T&) {
  14.                     std::cout << "all"<< std::endl;
  15.             }
  16.     };
  17.  
  18.     template<typename T>
  19.     struct Helper<T, typename std::enable_if<is_int_or_float<T>::value>::type> { // (3)
  20.             static void go(const T&) {
  21.                     std::cout << "int or float" << std::endl;
  22.             }
  23.     };
  24.  
  25.     template<typename T>
  26.     struct Helper<T, typename std::enable_if<std::is_pointer<T>::value>::type> { // (3)
  27.             static void go(const T&) {
  28.                     std::cout << "pointer" << std::endl;
  29.             }
  30.     };
  31.  
  32.     template<typename T>
  33.     void func(const T& arg) {
  34.             Helper<T>::go(arg); // (1)
  35.     }
  36.     int main() {
  37.             char c;
  38.             int i;
  39.             float f; 
  40.             int* p;
  41.             func(c);
  42.             func(i);
  43.             func(f);
  44.             func(p);
  45.     }
  46.  
Success #stdin #stdout 0s 3340KB
comments (?)
stdin
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Standard input is empty
stdout
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all
int or float
int or float
pointer
https://ideone.com/XdePmg
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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