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Like this: Dictionary<int, Func<string, bool>>. This allows you to store functions that take a string parameter and return boolean. dico[5] = foo => foo == "Bar"; Or if the function is not anonymous: dico[5] = Foo; where Foo is defined like this: public bool Foo(string bar) {.
Code sample
private object function2(object arg1) { return null; }private object function3(object arg1, object arg3) { return null; }Dictionary<string, Func<State, object>> functions;public Interceptor() {functions = new Dictionary<string, Func<State, object>>();...- Definition
- Examples
- Remarks
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Namespace:\tSystem.Collections.Generic
Assembly:\tSystem.Collections.dll
Assembly:\tmscorlib.dll
Assembly:\tnetstandard.dll
Represents a collection of keys and values. public class Dictionary : System.Collections.Generic.ICollection >, System.Collections.Generic.IDictionary , System.Collections.Generic.IEnumerable >, System.Collections.Generic.IReadOnlyCollection >, System.Collections.Generic.IReadOnlyDictionary , System.Collections.IDictionary public class Dictionary : System.Collections.Generic.ICollection >, System.Collections.Generic.IDictionary , System.Collections.Generic.IEnumerable >, System.Collections.Generic.IReadOnlyCollection >, System.Collections.Generic.IReadOnlyDictionary , System.Collections.IDictionary, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable [System.Runtime.InteropServices.ComVisible(false)] [System.Serializable] public class Dictionary : System.Collections.Generic.ICollection >, System.Collections.Generic.IDictionary , System.Collections.Generic.IEnumerable >, System.Collections.IDictionary, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable [System.Runtime.InteropServices.ComVisible(false)] [System.Serializable] public class Dictionary : System.Collections.Generic.ICollection >, System.Collections.Generic.IDictionary , System.Collections.Generic.IEnumerable >, System.Collections.Generic.IReadOnlyCollection >, System.Collections.Generic.IReadOnlyDictionary , System.Collections.IDictionary, System.Runtime.Serialization.IDeserializationCallback, System.Runtime.Serialization.ISerializable type Dictionary<'Key, 'Value> = class interface ICollection<'Key, 'Value>> interface seq<'Key, 'Value>> interface IEnumerable interface IDictionary<'Key, 'Value> interface IReadOnlyCollection<'Key, 'Value>> interface IReadOnlyDictionary<'Key, 'Value> interface ICollection interface IDictionary type Dictionary<'Key, 'Value> = class interface ICollection<'Key, 'Value>> interface seq<'Key, 'Value>> interface IEnumerable interface IDictionary<'Key, 'Value> interface IReadOnlyCollection<'Key, 'Value>> interface IReadOnlyDictionary<'Key, 'Value> interface ICollection interface IDictionary interface IDeserializationCallback interface ISerializable [ ] [ ] type Dictionary<'Key, 'Value> = class interface IDictionary<'Key, 'Value> interface ICollection<'Key, 'Value>> interface seq<'Key, 'Value>> interface IDictionary interface ICollection interface IEnumerable interface ISerializable interface IDeserializationCallback [ ] [ ] type Dictionary<'Key, 'Value> = class interface IDictionary<'Key, 'Value> interface ICollection<'Key, 'Value>> interface IDictionary interface ICollection interface IReadOnlyDictionary<'Key, 'Value> interface IReadOnlyCollection<'Key, 'Value>> interface seq<'Key, 'Value>> interface IEnumerable interface ISerializable interface IDeserializationCallback [ ] [ ] type Dictionary<'Key, 'Value> = class interface IDictionary<'Key, 'Value> interface ICollection<'Key, 'Value>> interface seq<'Key, 'Value>> interface IEnumerable interface IDictionary interface ICollection interface IReadOnlyDictionary<'Key, 'Value> interface IReadOnlyCollection<'Key, 'Value>> interface ISerializable interface IDeserializationCallback type Dictionary<'Key, 'Value> = class interface IDictionary<'Key, 'Value> interface ICollection<'Key, 'Value>> interface IReadOnlyDictionary<'Key, 'Value> interface IReadOnlyCollection<'Key, 'Value>> interface seq<'Key, 'Value>> interface IDictionary interface ICollection interface IEnumerable Public Class Dictionary(Of TKey, TValue) Implements ICollection(Of KeyValuePair(Of TKey, TValue)), IDictionary, IDictionary(Of TKey, TValue), IEnumerable(Of KeyValuePair(Of TKey, TValue)), IReadOnlyCollection(Of KeyValuePair(Of TKey, TValue)), IReadOnlyDictionary(Of TKey, TValue) Public Class Dictionary(Of TKey, TValue) Implements ICollection(Of KeyValuePair(Of TKey, TValue)), IDeserializationCallback, IDictionary, IDictionary(Of TKey, TValue), IEnumerable(Of KeyValuePair(Of TKey, TValue)), IReadOnlyCollection(Of KeyValuePair(Of TKey, TValue)), IReadOnlyDictionary(Of TKey, TValue), ISerializable Public Class Dictionary(Of TKey, TValue) Implements ICollection(Of KeyValuePair(Of TKey, TValue)), IDeserializationCallback, IDictionary, IDictionary(Of TKey, TValue), IEnumerable(Of KeyValuePair(Of TKey, TValue)), ISerializable Type Parameters
TKey
The following code example creates an empty Dictionary of strings with string keys and uses the Add method to add some elements. The example demonstrates that the Add method throws an ArgumentException when attempting to add a duplicate key.
The 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 shows how to use the TryGetValue method as a more efficient way to retrieve values if a program often must try key values that are not in the dictionary, and it shows how to use the ContainsKey method to test whether a key exists before calling the Add method.
The example shows how to enumerate the keys and values in the dictionary and how to enumerate the keys and values alone using the Keys property and the Values property.
The Dictionary generic class provides a mapping from a set of keys to a set of values. Each addition to the dictionary consists of a value and its associated key. Retrieving a value by using its key is very fast, close to O(1), because the Dictionary class is implemented as a hash table.
As long as an object is used as a key in the Dictionary , it must not change in any way that affects its hash value. Every key in a Dictionary must be unique according to the dictionary's equality comparer. A key cannot be null, but a value can be, if its type TValue is a reference type.
Dictionary requires an equality implementation to determine whether keys are equal. You can specify an implementation of the IEqualityComparer generic interface by using a constructor that accepts a comparer parameter; if you do not specify an implementation, the default generic equality comparer EqualityComparer .Default is used. If type TKey implements the System.IEquatable generic interface, the default equality comparer uses that implementation.
The capacity of a Dictionary is the number of elements the Dictionary can hold. As elements are added to a Dictionary , the capacity is automatically increased as required by reallocating the internal array.
.NET Framework only: For very large Dictionary objects, you can increase the maximum capacity to 2 billion elements on a 64-bit system by setting the enabled attribute of the configuration element to true in the run-time environment.
For purposes of enumeration, each item in the dictionary is treated as a KeyValuePair structure representing a value and its key. The order in which the items are returned is undefined.
A Dictionary can support multiple readers concurrently, as long as the collection is not modified. Even so, enumerating through a collection is intrinsically not a thread-safe procedure. In the rare case where an enumeration contends with write accesses, the collection must be locked during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.
For thread-safe alternatives, see the ConcurrentDictionary class or ImmutableDictionary class.
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Jan 26, 2023 · To initialize a dictionary in C#, we first need to provide the type for the key and the type for the value. For example, for a dictionary that stores the name and age of a person, the initialization would be: C# Dictionary<string, int> nameToAge = new Dictionary<string, int>(); The first type inside the angle brackets is the key type.
Jul 5, 2023 · C# Dictionary tutorial shows how to work with a Dictionary collection in C#. A dictionary, also called an associative array, is a collection of unique keys and a collection of values, where each key is associated with one value. Retrieving and adding values is very fast. Dictionaries take more memory because for each value there is also a key.
Jul 11, 2023 · For those that don’t know Microsoft have introduced new FrozenDictionary and FrozenSet collections in .NET 8 (from Preview 1). These collections will reside in the System. Collections. Frozen namespace and are collections which are performance optimized for READ ONLY scenarios. Just for fun I ran some benchmarks (code below) to compare the ...
Aug 16, 2023 · In C#, the ` Dictionary<TKey, TValue> ` class from the ` System.Collections.Generic ` namespace provides a powerful implementation of this data structure. This post we delve into the technical aspects of the C# Dictionary class, highlighting its features, usage scenarios, and performance considerations. Anatomy of the Dictionary Class:
Apr 21, 2023 · This form of dictionary allows you to add and remove entries at will: myDictionary.Add(1, "stuff"); myDictionary.TryAdd(1, "stuff"); // You only remove via the key myDictionary.Remove(1); myDictionary.Clear(); you can find items in a dictionary in a few different ways (though I'd probably avoid linq):
