User:Nate/live example

• Template:test_live_example
• Template:livecodelink

Example

The following example uses a lambda function to increment all of the elements of a vector and then computes a sum of them:

<livecodelink compiler="clangpp" text="run this code">#include <vector>

1. include <algorithm>
2. include <iostream>

struct Sum {

   Sum() { sum = 0; }
   void operator()(int n) { sum += n; }

   int sum;

};

int main() {

   std::vector<int> nums{3, 4, 2, 9, 15, 267};

   std::cout << "before: ";
   for (auto n : nums) {
       std::cout << n << " ";
   }
   std::cout << '\n';

   std::for_each(nums.begin(), nums.end(), [](int &n){ n++; });
   Sum s = std::for_each(nums.begin(), nums.end(), Sum());

   std::cout << "after:  ";
   for (auto n : nums) {
       std::cout << n << " ";
   }
   std::cout << '\n';
   std::cout << "sum: " << s.sum << '\n';

}</livecodelink>

#include <vector>
#include <algorithm>
#include <iostream>

struct Sum {
    Sum() { sum = 0; }
    void operator()(int n) { sum += n; }

    int sum;
};

int main()
{
    std::vector<int> nums{3, 4, 2, 9, 15, 267};

    std::cout << "before: ";
    for (auto n : nums) {
        std::cout << n << " ";
    }
    std::cout << '\n';

    std::for_each(nums.begin(), nums.end(), [](int &n){ n++; });
    Sum s = std::for_each(nums.begin(), nums.end(), Sum());

    std::cout << "after:  ";
    for (auto n : nums) {
        std::cout << n << " ";
    }
    std::cout << '\n';
    std::cout << "sum: " << s.sum << '\n';
}

Output:

before: 3 4 2 9 15 267
after:  4 5 3 10 16 268
sum: 306