如何通过函数上的键获取字典值?
我的函数代码(和我尝试的命令不工作):
static void XML_Array(Dictionary<string, string> Data_Array)
{
String xmlfile = Data_Array.TryGetValue("XML_File", out value);
}
我的按钮代码:
private void button2_Click(object sender, EventArgs e)
{
Dictionary<string, string> Data_Array = new Dictionary<string, string>();
Data_Array.Add("XML_File", "Settings.xml");
XML_Array(Data_Array);
}
我想对XML_Array函数的变量是:
string xmlfile = "Settings.xml":
当前回答
其实很简单:
String xmlfile = Data_Array["XML_File"];
注意，如果字典没有等于“XML_File”的键，代码将抛出异常。如果你想先检查，你可以像这样使用TryGetValue:
string xmlfile;
if (!Data_Array.TryGetValue("XML_File", out xmlfile)) {
// the key isn't in the dictionary.
return; // or whatever you want to do
}
// xmlfile is now equal to the value
其他回答
Dictionary<String, String> d = new Dictionary<String, String>();
d.Add("1", "Mahadev");
d.Add("2", "Mahesh");
Console.WriteLine(d["1"]); // It will print Value of key '1'
static void XML_Array(Dictionary<string, string> Data_Array)
{
String value;
if(Data_Array.TryGetValue("XML_File", out value))
{
// ... Do something here with value ...
}
}
其实很简单:
String xmlfile = Data_Array["XML_File"];
注意，如果字典没有等于“XML_File”的键，代码将抛出异常。如果你想先检查，你可以像这样使用TryGetValue:
string xmlfile;
if (!Data_Array.TryGetValue("XML_File", out xmlfile)) {
// the key isn't in the dictionary.
return; // or whatever you want to do
}
// xmlfile is now equal to the value
Dictionary<int,string> dict = new Dictionary<int,string>{
{1,"item1"},
{2,"item2"},
{3,"item3"},
}
int key = 2 // for example
string result = dict.ContainsKey(key) ? dict[key] : null;
(我在另一个问题上发布了这个，我不知道如何链接到它，所以在这里) Dictionary<K,V>扩展。我已经用了很长时间了::
public static bool TryGetKey<K, V>(this IDictionary<K, V> instance, V value, out
K key)
{
foreach (var entry in instance)
{
if (!entry.Value.Equals(value))
{
continue;
}
key = entry.Key;
return true;
}
key = default(K);
return false;
}
并使用as:
public static void Main()
{
Dictionary<string, string> dict = new Dictionary<string, string>()
{
{"1", "one"},
{"2", "two"},
{"3", "three"}
};
string value="two";
if (dict.TryGetKey(value, out var returnedKey))
Console.WriteLine($"Found Key {returnedKey}");
else
Console.WriteLine($"No key found for value {value}");
}
