fork download
copy 
  1. #include <iostream>
  2. #include <map>
  3. using namespace std;
  4.  
  5. struct CompareString
  6. {
  7.     using is_transparent = void;
  8.  
  9.     bool operator()(const std::string& l, const string& r) const
  10.     {
  11.         return l.compare(r) < 0;
  12.     }
  13.  
  14.     template<typename T>
  15.     bool operator()(const std::string& l, const T& r) const
  16.     {
  17.         return l.compare(r) < 0;
  18.     }
  19.  
  20.     template<typename T>
  21.     bool operator()(const T& l, const std::string& r) const
  22.     {
  23.         return r.compare(l) > 0;
  24.     }
  25. };
  26.  
  27. using StrStrMap = std::map<std::string,std::string, CompareString>;
  28.  
  29. template<typename K> 
  30. const std::string* findPtr(const StrStrMap& c, const K& k) {
  31.     auto iter = c.find(k);
  32.     if (iter == c.end()) return nullptr;
  33.     return &iter->second;
  34. }
  35.  
  36. const std::string& fromPtr(const std::string* s) {
  37.     static const std::string def{"(null)"};
  38.     if (!s) return def;
  39.     return *s;
  40. }
  41.  
  42.  
  43. int main() {
  44.     StrStrMap m{{"abc", "123"}, {"def", "456"}};
  45.     const char kctrl1[] = "abc";
  46.     const std::string kstd1 = "abc";
  47.  
  48.     cout << __LINE__ << " " << fromPtr(findPtr(m, kstd1)) << endl;
  49.     cout << __LINE__ << " " << fromPtr(findPtr(m, kctrl1)) << endl;
  50.  
  51.     auto it = m.find(kstd1);
  52.     if (it != m.end()) cout << it->second << endl;
  53.  
  54.     return 0;
  55. }
Success #stdin #stdout 0s 4312KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
48 123
49 123
123
https://ideone.com/QvTPXp
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!