C# · 12月 26, 2021

c# – 检查空或空列表

我有一个列表,有时它是空的或是空的.我想要检查它是否包含任何字符串,如果没有,然后添加一个字符串到列表. var myList = new List<string>(); // I have a list,sometimes it doesn’t have any data added to itif (myList == null) Console.WriteLine(“List is never null”); // Expression is always falseif (myList[0] == null) myList.Add(“new item”); // Index was out of range. Must be non-negative and less than the size of the collection.// Inner Exception says “null”解决方法 你需要这个: if(myList.Count == 0){ // nothing is there. Add here}

基本上新的List< T>不会为空,但不会有元素.