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  1. #include <algorithm>
  2. #include <iostream>
  3. #include <vector>
  4.  
  5. struct Even {
  6.  
  7.     void operator() (int n)
  8.     {
  9.         std::cout << n;
  10.  
  11.         if (n % 2 == 0) {
  12.             std::cout << " is even " << std::endl;
  13.             ++evenCount;
  14.         }
  15.         else {
  16.                 std::cout << " is odd " << std::endl;
  17.         }
  18.     }
  19.  
  20.     // To use a single copy and preserve
  21.     // value use static
  22.     static int evenCount;
  23. };
  24.  
  25. int Even::evenCount = 0;
  26.  
  27. int main()
  28. {
  29.     // Create a vector object that contains 10 elements.
  30.     std::vector<int> v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  31.  
  32.     // Count the number of even numbers in the vector
  33.  
  34.  
  35.     // Using function object
  36.     for_each(v.begin(), v.end(), Even());
  37.  
  38.     // Print the count of even numbers to the console.
  39.     std::cout << "There are " << Even::evenCount
  40.         << " even numbers in the vector." << std::endl;
  41.  
  42.     // Using lambda function
  43.     int evenCount = 0;
  44.  
  45.     for_each(v.begin(), v.end(),
  46.  
  47.             // The capture-list specifies what variables
  48.             // the lamba expression can use from outside.
  49.             [&evenCount] (int n)
  50.             {
  51.                 std::cout << n;
  52.  
  53.                 if (n % 2 == 0) {
  54.                     std::cout << " is even " << std::endl;
  55.                     ++evenCount;
  56.                 }
  57.                 else {
  58.                         std::cout << " is odd " << std::endl;
  59.                 }
  60.             }
  61.     );
  62.  
  63.     // Print the count of even numbers to the console.
  64.     std::cout << "There are " << evenCount
  65.         << " even numbers in the vector." << std::endl;
  66. }
  67.  
Success #stdin #stdout 0s 3476KB
comments (?)
stdin
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Standard input is empty
stdout
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1 is odd 
2 is even 
3 is odd 
4 is even 
5 is odd 
6 is even 
7 is odd 
8 is even 
9 is odd 
10 is even 
There are 5 even numbers in the vector.
1 is odd 
2 is even 
3 is odd 
4 is even 
5 is odd 
6 is even 
7 is odd 
8 is even 
9 is odd 
10 is even 
There are 5 even numbers in the vector.
https://ideone.com/d6MWbA
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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