C#合并两个Dictionary的方法

public Dictionary<string, string> MergeDictionary(Dictionary<string, string> first, Dictionary<string, string> second)
{
if (first == null) first = new Dictionary<string, string>();
if (second == null) return first;

//相对于第一种只是修改了遍历的方法
foreach (string key in second.Keys)
{
if (!first.ContainsKey(key))
first.Add(key,second[key]);
}
return first;
}