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  1. #include <unordered_map>
  2. #include <string>
  3. #include <iostream>
  4.  
  5. template<typename Map, typename T>
  6. std::pair<typename Map::iterator, bool>
  7. insert_or_assign(Map& m, const typename Map::key_type& k, const T& t)
  8. {
  9.     auto p = m.insert({k, t});
  10.     if (!p.second) {
  11.         // overwrite previous value
  12.         p.first->second = t;
  13.     }
  14.     return p;
  15. }
  16.  
  17. int main() {
  18.   auto map = std::unordered_map<std::string, int>{{"foo", 1}, {"bar", 2}};
  19.  
  20.   auto p = map.insert({"foo", 3});
  21.   if (p.second) {
  22.     // it has just been inserted.
  23.     std::cout << "foo was inserted\n";
  24.   } else {
  25.     // it has been assigned
  26.     std::cout << "foo was assigned\n";
  27.   }
  28.  
  29.   p = map.insert({"hi", 42});
  30.   if (p.second) {
  31.     // it has just been inserted.
  32.     std::cout << "hi was inserted\n";
  33.   } else {
  34.     // it has been assigned
  35.     std::cout << "hi was assigned\n";
  36.   }
  37.  
  38. }
Success #stdin #stdout 0s 3464KB
comments (?)
stdin
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Standard input is empty
stdout
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foo was assigned
hi was inserted
https://ideone.com/Ym8Dyx
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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