C # List The value change passed as a parameter demonstration commentary

[testmethod]public void TestMethod1 () {    list<int> List = new list<int> ();    Test (list);    Console.WriteLine (list. Count ()); The total quantity becomes 1}private void Test (list<int> list) {    list. ADD (1);}

Can be found: After the Test, the list of the number of elements from 0 to 1.

If you assign a variable list to another variable list2, the list will change if you manipulate List2.

This is because these variables are actually pointing to another block of memory, and the change in the number of elements and the value of the element is the same block of memory that corresponds to the change.

But by calling their ConvertAll method, the returned variable is pointing to another block of memory, which is different from the previous one.

[testmethod]public void TestMethod1 () {    list<int> List = new list<int> ();    Test (list);    Console.WriteLine (list. Count ()); The total quantity is still 0}private void Test (list<int> list) {    list<int> list2 = new list<int> ();    List2. ADD (1);        list = List2;}

The above code is different, this is the list = List2, in fact, the list points to the list2 corresponding memory block, according to the previous conclusion, this time the list of parameters and List2 is a bunch, instead of and TestMethod1 in the list of the gang.

The following code is different, but now we have actually created two new list<int> () and no one is using it in TESTMETHOD1 ().

[testmethod]public void TestMethod1 () {    list<int> List = new list<int> ();    Test (ref list);    Console.WriteLine (list. Count ()); The total quantity becomes 1}private void Test (ref list<int> List) {    list<int> list2 = new list<int> ();    List2. ADD (1);        list = List2;}

Arrays are the same thing.