Using lambda expressions in function templates - C++ STL

C++ examples for STL:Lambda

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Description

Using lambda expressions in function templates

Demo Code

#include <iostream>
#include <iomanip>
#include <vector>
#include <functional>
#include <cmath>                            // For pow()
using std::vector;

template <typename T> void setValues(vector<T>& vec, std::function<void(T&)> fun) {
  for (int i{}; i < vec.size(); ++i)
    fun(vec[i]);// www  . ja  va 2s  . c o m
}

template<class T> void listVector(const vector<T>& vec) {
  int count{};
  const int valuesPerLine{ 5 };
  auto print = [&count, valuesPerLine](T value) {
    std::cout << std::setw(10) << value << "  ";
    if (++count % valuesPerLine == 0)
      std::cout << std::endl;
  };
  for (int i{}; i < vec.size(); ++i)
    print(vec[i]);
}

int main()
{

  vector<int> integerData(50);

  int current{ 1 };

  int increment{ 1 };

  setValues<int>(integerData, [increment, &current](int& v) mutable { v = current + increment++; current = v; });

  std::cout << "Integer vector contains :" << std::endl;

  listVector(integerData);


  vector<double> values(10);

  int power{};

  double x{ 2.5 };

  setValues<double>(values, [power, x](double& v) mutable { v = std::pow(x, power++); });

  std::cout << "\nDouble vector contains:" << std::endl;

  listVector(values);
}

Result


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