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  1. #include <iostream>
  2.  
  3. union Union
  4. {
  5.     char c;
  6.     short s;
  7.     int i;
  8.     float f;
  9.     double d;
  10.  
  11.     operator char() const { std::cout << "getting char\n"; return c; }
  12.     operator short() const { std::cout << "getting short\n"; return s; }
  13.     operator int() const { std::cout << "getting int\n"; return i; }
  14.     operator float() const { std::cout << "getting float\n"; return f; }
  15.     operator double() const { std::cout << "getting double\n"; return d; }
  16.     template <typename T> operator T() const { std::cout << "error\n"; T t; return t; }
  17.  
  18.     Union &operator =(char ac) { c = ac; std::cout << "set char\n"; return *this; }
  19.     Union &operator =(short as) { s = as; std::cout << "set short\n"; return *this; }
  20.     Union &operator =(int ai) { i = ai; std::cout << "set int\n"; return *this; }
  21.     Union &operator =(float af) { f = af; std::cout << "set float\n"; return *this; }
  22.     Union &operator =(double ad) { d = ad; std::cout << "set double\n"; return *this; }
  23.     template <typename T> Union &operator =(T at) { std::cout << "error!\n"; return *this; }
  24. };
  25.  
  26. template <typename T>
  27. void doSomething(Union a, const Union b)
  28. {
  29.   a = static_cast<T>(b);
  30. }
  31.  
  32. int main(int argc, char **argv)
  33. {
  34.     Union a, b;
  35.  
  36.     doSomething<int>(a, b);
  37.     doSomething<char>(a, b);
  38.     doSomething<char *>(a, b);
  39.  
  40.     return 0;
  41. }
  42.  
Success #stdin #stdout 0.02s 2724KB
comments (?)
stdin
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Standard input is empty
stdout
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getting int
set int
getting char
set char
error
error!
https://ideone.com/JBK1nx
union con operadores sobrecargados que avisan de error si se trabaja inadecuadamente con ella
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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