迭代字典的最佳方法是什么？

#1 楼

 foreach(KeyValuePair<string, string> entry in myDictionary)
{
    // do something with entry.Value or entry.Key
}
 

#2 楼

foreach(var item in myDictionary)
{
  foo(item.Key);
  bar(item.Value);
}

foreach(var item in myDictionary.Keys)
{
  foo(item);
}

foreach(var item in myDictionary.Values)
{
  foo(item);
}

#3 楼

for (int index = 0; index < dictionary.Count; index++) {
  var item = dictionary.ElementAt(index);
  var itemKey = item.Key;
  var itemValue = item.Value;
}

#4 楼

// 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);
}

#5 楼

foreach (var kvp in items)
{
    // key is kvp.Key
    doStuff(kvp.Value)
}

foreach (var item in items.Values)
{
    doStuff(item)
}

foreach (var kvp in items.OrderBy(kvp => kvp.Key))
{
    // key is kvp.Key
    doStuff(kvp.Value)
}

foreach (var item in items.OrderBy(kvp => kvp.Key).Select(kvp => kvp.Value))
{
    doStuff(item)
}

#6 楼

foreach(var kvp in my_dictionary) {
  ...
}

#7 楼

var dic = new Dictionary<int, string>() { { 1, "One" }, { 2, "Two" }, { 3, "Three" } };
foreach (var (key, value) in dic) {
    Console.WriteLine($"Item [{key}] = {value}");
}
//Or
foreach (var (_, value) in dic) {
    Console.WriteLine($"Item [NO_ID] = {value}");
}
//Or
foreach ((int key, string value) in dic) {
    Console.WriteLine($"Item [{key}] = {value}");
}

#8 楼

dictionary
.AsParallel()
.ForAll(pair => 
{ 
    // Process pair.Key and pair.Value here
});

#9 楼

public static string Normal(Dictionary<string, string> dictionary)
{
    string value;
    int count = 0;
    foreach (var kvp in dictionary)
    {
        value = kvp.Value;
        count++;
    }

    return "Normal";
}

public static string Keys(Dictionary<string, string> dictionary)
{
    string value;
    int count = 0;
    foreach (var key in dictionary.Keys)
    {
        value = dictionary[key];
        count++;
    }

    return "Keys";
}

private static string RunTest<T>(T dictionary, Func<T, string> function)
{            
    DateTime start = DateTime.Now;
    string name = null;
    for (int i = 0; i < 10; i++)
    {
        name = function(dictionary);
    }
    DateTime end = DateTime.Now;
    var duration = end.Subtract(start);
    return string.Format("{0} took {1} seconds", name, duration.TotalSeconds);
}

#10 楼

Dictionary<string, object> myDictionary = new Dictionary<string, object>();
// Populate your dictionary here

foreach (KeyValuePair<string,object> kvp in myDictionary)
{
     // Do some interesting things
}

#11 楼

var fruits = new Dictionary<string, int>();
...
foreach (var (fruit, number) in fruits)
{
    Console.WriteLine(fruit + ": " + number);
}

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;
    }
}

#12 楼

public static void Deconstruct<TKey, TVal>(this KeyValuePair<TKey, TVal> pair, out TKey key, out TVal value)
{
   key = pair.Key;
   value = pair.Value;
}

// Dictionary can be of any types, just using 'int' and 'string' as examples.
Dictionary<int, string> dict = new Dictionary<int, string>();

// Deconstructor gets called here.
foreach (var (key, value) in dict)
{
   Console.WriteLine($"{key} : {value}");
}

#13 楼

Dictionary<string,object> myDictionary = new Dictionary<string,object>();
//Populate your dictionary here

foreach (KeyValuePair<string,object> kvp in myDictionary) {
    //Do some interesting things;
}

#14 楼

var dictionary = new Dictionary<int, string>();

// ...

foreach (var (key, value) in dictionary)
{
    // ...
}

#15 楼

foreach(var item in myDictionary)
{ 
    Console.WriteLine(item.Key);
    Console.WriteLine(item.Value);
}

#16 楼

public static class IDictionaryExtensions
{
    public static IEnumerable<(TKey, TValue)> Tuples<TKey, TValue>(
        this IDictionary<TKey, TValue> dict)
    {
        foreach (KeyValuePair<TKey, TValue> kvp in dict)
            yield return (kvp.Key, kvp.Value);
    }
}

foreach (var(id, value) in dict.Tuples())
{
    // your code using 'id' and 'value'
}

foreach ((string id, object value) in dict.Tuples())
{
    // your code using 'id' and 'value'
}

foreach (KeyValuePair<string, object> kvp in dict)
{
    string id = kvp.Key;
    object value = kvp.Value;

    // your code using 'id' and 'value'
}

#17 楼

#18 楼

    public static void ForEach<T, U>(this Dictionary<T, U> d, Action<KeyValuePair<T, U>> a)
    {
        foreach (KeyValuePair<T, U> p in d) { a(p); }
    }

    public static void ForEach<T, U>(this Dictionary<T, U>.KeyCollection k, Action<T> a)
    {
        foreach (T t in k) { a(t); }
    }

    public static void ForEach<T, U>(this Dictionary<T, U>.ValueCollection v, Action<U> a)
    {
        foreach (U u in v) { a(u); }
    }

myDictionary.ForEach(pair => Console.Write($"key: {pair.Key}, value: {pair.Value}"));
myDictionary.Keys.ForEach(key => Console.Write(key););
myDictionary.Values.ForEach(value => Console.Write(value););

#19 楼

foreach (DictionaryEntry de in myDictionary)
{
     //Do some stuff with de.Value or de.Key
}

#20 楼

foreach(var value in dictionary.Values)
{
    // do something with entry.Value only
}

#21 楼

foreach(var entry in MyDic)
{
    // do something with entry.Value or entry.Key
}

#22 楼

foreach (DictionaryEntry entry in myDictionary)
{
     //Read entry.Key and entry.Value here
}

#23 楼

public new IEnumerator<T> GetEnumerator()
{
   return this.Values.GetEnumerator();
}

#24 楼

public static class DictionaryExtension
{
    public static void ForEach<T1, T2>(this Dictionary<T1, T2> dictionary, Action<T1, T2> action) {
        foreach(KeyValuePair<T1, T2> keyValue in dictionary) {
            action(keyValue.Key, keyValue.Value);
        }
    }
}

myDictionary.ForEach((x,y) => Console.WriteLine(x + " - " + y));

#25 楼

var dictionary = new Dictionary<string, int>
{
    { "Key", 12 }
};

var aggregateObjectCollection = dictionary.Select(
    entry => new AggregateObject(entry.Key, entry.Value));

#26 楼

Dictionary<String, Double> myProductPrices = new Dictionary<String, Double>();

//Add some entries to the dictionary

myProductPrices.ToList().ForEach(kvP => 
{
    kvP.Value *= 1.15;
    Console.Writeline(String.Format("Product '{0}' has a new price: {1} $", kvp.Key, kvP.Value));
});

var newProductPrices = myProductPrices.Select(kvp => new { Name = kvp.Key, Price = kvp.Value * 1.15 } );

#27 楼

Dictionary<int, string> dict = new Dictionary<int, string>();
dict.Add(1,"One");
dict.Add(2,"Two");
dict.Add(3,"Three");

foreach (KeyValuePair<int, string> item in dict)
{
    Console.WriteLine("Key: {0}, Value: {1}", item.Key, item.Value);
}

#28 楼

var keyList=new List<string>(dictionary.Keys);
for (int i = 0; i < keyList.Count; i++)
{
   var key= keyList[i];
   var value = dictionary[key];
 }

#29 楼

 Dictionary<int, string> dict = new Dictionary<int, string>();
 dict.Add(1, "American Ipa");
 dict.Add(2, "Weiss");
 dict.ToList().ForEach(x => Console.WriteLine($"key: {x.Key} | value: {x.Value}") );

#30 楼

foreach(KeyValuePair<string, string> entry in myDictionary)
{
    // do something with entry.Value or entry.Key
}

foreach(var entry in myDictionary)
{
    // do something with entry.Value or entry.Key
}

var myDictionary = new Dictionary<string, string>(x);//fill dictionary with x

foreach(var kvp in myDictionary)//iterate over dictionary
{
    // do something with kvp.Value or kvp.Key
}