如果密钥不存在，字典返回默认值[重复] - Dictionary returning a default value if the key does not exist [duplicate]

问题：

This question already has an answer here: 这个问题在这里已有答案：

• Is there an IDictionary implementation that, on missing key, returns the default value instead of throwing? 是否有一个IDictionary实现，在缺少键时，返回默认值而不是抛出？ 13 answers 13个答案

I find myself using the current pattern quite often in my code nowadays 我发现自己现在经常在我的代码中使用当前模式

var dictionary = new Dictionary<type, IList<othertype>>();
// Add stuff to dictionary

var somethingElse = dictionary.ContainsKey(key) ? dictionary[key] : new List<othertype>();
// Do work with the somethingelse variable

Or sometimes 或者有时候

var dictionary = new Dictionary<type, IList<othertype>>();
// Add stuff to dictionary

IList<othertype> somethingElse;
if(!dictionary.TryGetValue(key, out somethingElse) {
    somethingElse = new List<othertype>();
}

Both of these ways feel quite roundabout. 这两种方式都让人觉得很迂回。 What I really would like is something like 我真正想要的是这样的

dictionary.GetValueOrDefault(key)

Now, I could write an extension method for the dictionary class that does this for me, but I figured that I might be missing something that already exists. 现在，我可以为字典类编写一个扩展方法来为我做这个，但我想我可能会遗漏已经存在的东西。 SO, is there a way to do this in a way that is more "easy on the eyes" without writing an extension method to dictionary? 那么，有没有办法以更简单的方式做到这一点，而无需在字典中编写扩展方法？

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解决方案：

参考一： https://en.stackoom.com/question/AulJ
参考二： https://stackoom.com/question/AulJ