WebApr 9, 2024 · 使用TryGetValue更快,性能更好,因为只用了一次查找,TryGetValue 比 ContainsKey后使用[key]取value,速度快一倍; TryGetValue更安全,找不到value时返回false;而使用ContainsKey后使用[key]取value取不到时,会抛出异常导致真机卡死。 用法 WebMar 31, 2024 · TryGetValue("c", out result)) { Console.WriteLine(result); } // Part B: use inline "out string." if (values.TryGetValue("c", out string description)) { Console.WriteLine(description); }
c# - Retrieving Dictionary Value Best Practices - Stack Overflow
WebJul 10, 2024 · Since the dictionary needs to use a type parameter for its out argument, it has to use an attribute to indicate that even when a non-nullable type argument has been supplied for the TValue type parameter, when it comes to the TryGetValue method's out argument, the nullable form needs to be used. WebExamples. The following code example uses the Item[] property (the indexer in C#) to retrieve values, demonstrating that a KeyNotFoundException is thrown when a requested key is not present, and showing that the value associated with a key can be replaced.. The example also shows how to use the TryGetValue method as a more efficient way to … canada goose women\u0027s lorette parka
C#字典Dictionary的用法说明(注重性能版)-织梦云编程网
WebJan 24, 2024 · int currentCount; // currentCount will be zero if the key id doesn't exist.. someDictionary.TryGetValue (id, out currentCount); someDictionary [id] = currentCount + 1; This relies on the fact that the TryGetValue method sets value to the default value of its type if the key doesn't exist. In your case, the default value of int is 0, which is ... WebAug 26, 2024 · if (dict.TryGetValue("key", out var x)) { DoSomethingWith(x); } And of course it could be reduced to one line: if (dict.TryGetValue("key", out var x)) DoSomethingWith(x); If you have a default value for when the key doesn't exist, it can become: DoSomethingWith(dict.TryGetValue("key", out var x) ? x : defaultValue); WebFeb 23, 2024 · Usage: Dictionary dict = new Dictionary () { { 1, "one" }, { 3, "three" } }; string one = dict.GetValueOrDefault (1, "one"); string two = dict.GetValueOrDefault (2, "two"); string three = dict.GetValueOrDefault (3, "three"); fisher 4 center faucet