for each, for_each, for auto - concept clean

Clean up the concept through below examples.

1. normal method : for, iterator

2. for auto loop

3. for each loop

4. for_each

refer to this example

It would be better if I could handle the parallel loop.
This is next time.

Thank you.


< gist >

	http://study.marearts.com/2017/05/for-each-foreach-for-auto-concept-clean.html
	#include <stdio.h>
	#include <iostream>
	#include <vector>
	#include <time.h> //rand
	#include <algorithm> //for_each
	using namespace std;
	#define N 10
	void printfn(int e)
	{
	cout << e << endl;
	}
	class sumClass{
	public:
	sumClass() : sum(0),count(0){}
	int getSum() { return sum; }
	int getCount() { return count; }
	void operator()(int e){
	sum = sum + e;
	count++;
	}
	private:
	int sum;
	int count;
	};
	int main()
	{
	//////////
	//rand seed
	srand(time(0));
	//////////
	//////////
	//basic data
	vector< int > VectorInt;
	//data input
	for (int i = 0; i < 10; ++i)
	{
	VectorInt.push_back( rand() );
	}
	//////////
	//////////
	//data access and print
	//////////
	printf(" #1-1 basic method - indexing \n");
	for (int i = 0; i < VectorInt.size(); ++i)
	{
	cout << "[" << i << "] : " << VectorInt[i] << endl;
	//printf("[%d] : %d \n", i, VectorInt[i]);
	}
	printf("\n");
	//////////
	//////////
	printf(" #1-2 basic method - iterator \n");
	vector<int>::iterator it;
	int count = 0;
	for (it = VectorInt.begin(); it != VectorInt.end(); it++)
	{
	cout << "[" << count++ << "] : " << *it << endl;
	//printf("[%d] : %d \n", count++, *it);
	}
	printf("\n");
	//////////
	//////////
	printf(" #2 - for auto loop - c++11 \n");
	printf("style 1 \n");
	count = 0;
	for (auto it2 : VectorInt)
	{
	cout << "[" << count++ << "] : " << it2 << endl;
	}
	printf("\n");
	printf("style 2 - it is useful when element is class or structure \n");
	count = 0;
	for (auto &it2 : VectorInt)
	{
	cout << "[" << count++ << "] : " << it2 << endl;
	}
	printf("\n");
	printf("style 3 \n");
	count = 0;
	for (int it2 : VectorInt)
	{
	cout << "[" << count++ << "] : " << it2 << endl;
	}
	printf("\n");
	//////////
	//////////
	printf(" #3 - for each loop - c++11 \n");
	printf("style 1 \n");
	count = 0;
	for each(auto it3 in VectorInt)
	{
	cout << "[" << count++ << "] : " << it3 << endl;
	}
	printf("\n");
	printf("style 2 \n");
	count = 0;
	for each(auto& it3 in VectorInt)
	{
	cout << "[" << count++ << "] : " << it3 << endl;
	}
	printf("\n");
	printf("style 3 \n");
	count = 0;
	for each(int it3 in VectorInt)
	{
	cout << "[" << count++ << "] : " << it3 << endl;
	}
	//////////
	//////////
	printf("\n");
	printf(" #3 - for each loop - STL \n");
	printf("example 1\n");
	for_each(VectorInt.begin(), VectorInt.end(), printfn);
	printf("\n");
	printf("example 2\n");
	sumClass result = for_each(VectorInt.begin(), VectorInt.end(), sumClass());
	printf(" sum : %d, count = %d \n", result.getSum(), result.getCount());
	//////////
	return 0;
	}

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< /gist >