c# - 使用字典时如何避免运行时错误

Question

我有一段代码表示字典和搜索键数组。

Dictionary<string, string> items = new Dictionary<string, string>()
                                   {
                                     {"1","Blue"},
                                     {"2","Green"},
                                     {"3","White"}
                                    };

string[] keys = new[] { "1", "2", "3", "4" };

当我传递字典中不存在的键时，如何安全地避免运行时错误？

Answer 1

How to safely avoid the run time error when i pass a key that is not present in dictionary?

您还没有展示您目前是如何尝试这样做的，但是您可以使用 Dictionary<,>.TryGetValue :

foreach (string candidate in keys)
{
    string value;
    if (items.TryGetValue(candidate, out value))
    {
        Console.WriteLine("Key {0} had value {1}", candidate, value);
    }
    else
    {
        Console.WriteLine("No value for key {0}", candidate);
    }
}