代碼片段----std::for_each

例程

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

int add5(int &n)
{
	int re = n + 5;
	std::cout << re << " ";
	return n + 5;
}

class addClass
{
	const int m_a;
public:
	addClass(int _a) : m_a(_a)
	{}

	void operator()(int _val) const
	{
		_val += m_a;
		std::cout << _val << " ";
	}
};

int main()
{
	int a[10] = { 0,1,2,3,4,5,6,7,8,9 };
	std::vector<int> vec(std::begin(a), std::end(a));

	// 不改變 vec
	// 函數
	std::for_each(vec.begin(), vec.end(), add5);
	std::cout << std::endl;

	// 類
	std::for_each(vec.begin(), vec.end(), addClass(6));
	std::cout << std::endl;

	// lambda表達式
	std::vector<int> A(std::begin(a), std::end(a));
	std::vector<int> B(std::begin(a), std::end(a));
	std::for_each(vec.begin(), vec.end(), [&A, &B](int i) {
		A[i] = B[i] + 5;
		std::cout << "A["<<i<<"]=" <<A[i] << " ";
	});
	std::cout << std::endl;

	// show vec
	for (auto sub : vec)
		std::cout << sub << " ";
	std::cout << std::endl;

	// 改變vec
	std::for_each(vec.begin(), vec.end(), [&vec](int i) {
		vec[i] += 10;
	});

	// show vec
	for (auto sub:vec)
		std::cout << sub<< " " ;
	std::cout<<std::endl;

    return 0;
}

運行結果：

5 6 7 8 9 10 11 12 13 14
6 7 8 9 10 11 12 13 14 15
A[0]=5 A[1]=6 A[2]=7 A[3]=8 A[4]=9 A[5]=10 A[6]=11 A[7]=12 A[8]=13 A[9]=14
0 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19