Question

How to initialize alarray with specific elements from other alarray in C++

Answer 1

#include <iostream>
#include <valarray>

using std::cout;
using std::endl;

int main()
{
	std::valarray<int> va(15);

	for (int i = 0; i < 15; i++) va[i] = i;

	std::valarray<int> va_part = va[std::slice(2, 3, 5)];

	for (int i = 0; i < va_part.size(); i++)
		cout << va_part[i] << " ";

	cout << endl;

	return 0;
}


/*
run:

2 7 12

*/

 

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Answer 2

#include <iostream>
#include <valarray>

using std::cout;
using std::endl;

int main()
{
	std::valarray<int> va(20);

	for (int i = 0; i < 20; i++) va[i] = i;

	std::valarray<int> va_part = va[std::slice(2, 4, 5)];

	for (int i = 0; i < va_part.size(); i++)
		cout << va_part[i] << " ";

	cout << endl;

	return 0;
}


/*
run:

2 7 12 17

*/

 

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