我看到了一些不同的方法来迭代C#中的字典。有标准的方法吗?
当前回答
我将利用.NET 4.0+的优势,为最初接受的问题提供更新的答案:
foreach(var entry in MyDic)
{
// do something with entry.Value or entry.Key
}
其他回答
根据MSDN上的官方文档,迭代字典的标准方法是:
foreach (DictionaryEntry entry in myDictionary)
{
//Read entry.Key and entry.Value here
}
我将利用.NET 4.0+的优势,为最初接受的问题提供更新的答案:
foreach(var entry in MyDic)
{
// do something with entry.Value or entry.Key
}
取决于你是在寻找关键点还是值。。。
来自MSDN Dictionary(TKey,TValue)类描述:
// When you use foreach to enumerate dictionary elements,
// the elements are retrieved as KeyValuePair objects.
Console.WriteLine();
foreach( KeyValuePair<string, string> kvp in openWith )
{
Console.WriteLine("Key = {0}, Value = {1}",
kvp.Key, kvp.Value);
}
// To get the values alone, use the Values property.
Dictionary<string, string>.ValueCollection valueColl =
openWith.Values;
// The elements of the ValueCollection are strongly typed
// with the type that was specified for dictionary values.
Console.WriteLine();
foreach( string s in valueColl )
{
Console.WriteLine("Value = {0}", s);
}
// To get the keys alone, use the Keys property.
Dictionary<string, string>.KeyCollection keyColl =
openWith.Keys;
// The elements of the KeyCollection are strongly typed
// with the type that was specified for dictionary keys.
Console.WriteLine();
foreach( string s in keyColl )
{
Console.WriteLine("Key = {0}", s);
}
在.NET Framework 4.7中,可以使用分解
var fruits = new Dictionary<string, int>();
...
foreach (var (fruit, number) in fruits)
{
Console.WriteLine(fruit + ": " + number);
}
要使此代码在较低的C#版本上运行,请添加System.ValueTuple NuGet包并在某处编写
public static class MyExtensions
{
public static void Deconstruct<T1, T2>(this KeyValuePair<T1, T2> tuple,
out T1 key, out T2 value)
{
key = tuple.Key;
value = tuple.Value;
}
}
我在MSDN上DictionaryBase类的文档中找到了此方法:
foreach (DictionaryEntry de in myDictionary)
{
//Do some stuff with de.Value or de.Key
}
这是我唯一能够在从DictionaryBase继承的类中正确运行的一个。