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  1. #include <stdexcept>
  2. #include <iostream>
  3. #include <string>
  4. #include <map>
  5.  
  6. typedef std::map<std::string, double> map_type ;
  7.  
  8. const double smoothingFactor = .5 ;
  9.  
  10. double addDataPoint(map_type & m, map_type::value_type data)
  11. {
  12.     map_type::iterator it = m.find(data.first) ;
  13.  
  14.     if ( it == m.end() )
  15.     {
  16.         m[data.first] = data.second ;
  17.         return data.second ;
  18.     }
  19.  
  20.     return it->second = smoothingFactor * data.second + (1-smoothingFactor) * it->second ;
  21. }
  22.  
  23. double getAverage(const map_type& m, const map_type::key_type & key )
  24. {
  25.     map_type::const_iterator it = m.find(key) ;
  26.     if ( it == m.end() )
  27.         throw std::logic_error( "getAverage called for non-existent key: \"" + key + '"') ;
  28.     return it->second ;
  29. }
  30.  
  31. std::ostream& operator<<(std::ostream& os, const map_type & map )
  32. {
  33.     map_type::const_iterator it ;
  34.     for ( it = map.begin(); it != map.end(); ++it )
  35.         os << it->first << ": " << it->second << '\n' ;
  36.     return os ;
  37. }
  38.  
  39. int main()
  40. {
  41.     map_type emaMap ;
  42.  
  43.     try
  44.     {
  45.         std::cout << "addDataPoint(\"a\", 4)\n" ;
  46.         addDataPoint(emaMap, std::make_pair("a", 4)) ;
  47.         std::cout << emaMap << '\n' ;
  48.  
  49.         std::cout << "addDataPoint(\"b\", 8)\n" ;
  50.         addDataPoint(emaMap, std::make_pair("b", 8)) ;
  51.         std::cout << emaMap << '\n' ;
  52.  
  53.         std::cout << "addDataPoint(\"a\", 6)\n" ;
  54.         addDataPoint(emaMap, std::make_pair("a", 6)) ;
  55.         std::cout << emaMap << '\n' ;
  56.  
  57.         std::cout << "addDataPoint(\"b\", 12)\n" ;
  58.         addDataPoint(emaMap, std::make_pair("b", 12)) ;
  59.         std::cout << emaMap << '\n' ;
  60.  
  61.         std::cout << "getAverage(\"a\")\n" ;
  62.         std::cout << getAverage(emaMap, "a") << "\n\n" ;
  63.  
  64.         std::cout << "getAverage(\"b\")\n" ;
  65.         std::cout << getAverage(emaMap, "b") << "\n\n" ;
  66.  
  67.         std::cout << "getAverage(\"c\")\n" ;
  68.         std::cout << getAverage(emaMap, "c") << "\n\n" ;
  69.     }
  70.     catch (std::exception& ex)
  71.     {
  72.         std::cout << ex.what() << '\n' ;
  73.     }
  74. }
  75.  
Success #stdin #stdout 0s 2992KB
comments (?)
stdin
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Standard input is empty
stdout
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addDataPoint("a", 4)
a: 4

addDataPoint("b", 8)
a: 4
b: 8

addDataPoint("a", 6)
a: 5
b: 8

addDataPoint("b", 12)
a: 5
b: 10

getAverage("a")
5

getAverage("b")
10

getAverage("c")
getAverage called for non-existent key: "c"
https://ideone.com/XXD34x
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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