C# 如何将一个List转换为只读的

如题，主要使用AsReadOnly这个方法就可以了

List<int> a = new List<int> {1, 2, 3, 4, 5}; 

 

IList<int> b = a.AsReadOnly(); // block modification... 

 

IList<int> c = b.AsWritable(); // ... but unblock it again 

 

c.Add(6); 

Debug.Assert(a.Count == 6); // we've modified the original 

 

IEnumerable<int> d = a.Select(x => x); // okay, try this... 

 

IList<int> e = d.AsWritable(); // no, can still get round it 

 

e.Add(7);