So If I have these two arrays:
int array1[] = {1, 2 ,3};
int array2[] = {1, 2, 3, 4, 5};
How do I check if 1, 2 and 3 from array1 are in array2? `
Thanks in advance.
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3You do know that Python code is actually wrong?UnholySheep– UnholySheep2016-10-15 22:40:16 +00:00Commented Oct 15, 2016 at 22:40
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@UnholySheep Probably is. Haven't touched python in so long.TCG– TCG2016-10-15 22:44:24 +00:00Commented Oct 15, 2016 at 22:44
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1In that case you should probably remove that statement about Python completely, as it is misleading (and in fact straight up wrong - Python does not have built-in syntax to check if one list is part of another).UnholySheep– UnholySheep2016-10-15 23:05:06 +00:00Commented Oct 15, 2016 at 23:05
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2 Answers
if (std::includes(std::begin(array2), std::end(array2),
std::begin(array1), std::end(array1)) {
// array2 includes array1
}
This requires the arrays are sorted, which yours are. Also, if they are sorted with some custom comparator, you must pass that to std::includes as well.
It is worth pointing out that I use your arrays the "wrong" way round; the algorithm expects its first range to be the larger one.
1 Comment
TCG
Thank you, looks easy to use.
You can use std::set_intersection. It requires the arrays to be sorted using the same comparator, though.
example from cppreference:
std::vector<int> v1{1,2,3,4,5,6,7,8};
std::vector<int> v2{ 5, 7, 9,10};
std::sort(v1.begin(), v1.end());
std::sort(v2.begin(), v2.end());
std::vector<int> v_intersection;
std::set_intersection(v1.begin(), v1.end(),
v2.begin(), v2.end(),
std::back_inserter(v_intersection));
for(int n : v_intersection)
std::cout << n << ' ';
