c# nested dictionary - 字典中的字典返回错误 (KeyNotFoundException)

Question

当我尝试在 visual studio 2012 下的 asp.net web api 项目中使用 C# 中的嵌套字典时出现错误代码。此代码示例实际上是从其他支持者在 stack-overflow 上引用的。同样的方法适用于普通字典，但不适用于嵌套字典。

-谢谢

示例代码:

Dictionary<string, Dictionary<string, string>> nest_dict = new Dictionary<string, Dictionary<string, string>>();
nest_dict["a1"]["b1"] = "nest dict test string value";

An exception of type 'System.Collections.Generic.KeyNotFoundException' occurred in mscorlib.dll but was not handled in user code

Answer 1

您应该首先初始化“嵌套”字典:

Dictionary<string, Dictionary<string, string>> nest_dict = new Dictionary<string, Dictionary<string, string>>();
nest_dict["a1"] = new Dictionary<string, string>();
nest_dict["a1"]["b1"] = "nest dict test string value";