集合的并集是合并集合的项，如下图所示：
image.png
List<int> ls1 = new List<int>() { 1,2,3,5,7,9 };
List<int> ls2 = new List<int>() { 2,4,6,8,9,10};
IEnumerable<int> unionLs = ls1.Union(ls2);
foreach (int item in unionLs)
{
Console.Write("{0}\t", item);
}
image.png
集合的交集是取集合的共同的项，如下图所示：
image.png
List<int> ls1 = new List<int>() { 1,2,3,5,7,9 };
List<int> ls2 = new List<int>() { 2,4,6,8,9,10};
IEnumerable<int> intersectLs = ls1.Intersect(ls2);
foreach (int item in intersectLs)
{
Console.Write("{0}\t",item);
}
image.png
image.png
