KeyValuePair<TKey,TValue> Struct

Namespace: System.Collections.Generic

Represents a key-value pair that can be returned by an IDictionary<TKey,TValue> or enumerated by a Dictionary<TKey,TValue>.

Syntax

public struct KeyValuePair<TKey,TValue>

Type Parameters

TKey: The type of the key in the key-value pair.

TValue: The type of the value in the key-value pair.

Constructors

Name	Description
`KeyValuePair<TKey,TValue> (TKey key, TValue value)`	Initializes a new instance of the `KeyValuePair<TKey,TValue>` structure.

Properties

Name	Description
`Key`	Gets the key of the key-value pair.
`Value`	Gets the value of the key-value pair.

Methods

Name	Description
`CompareTo(object obj)`	Compares the current instance with another object of the same type and returns an integer that indicates whether the current instance precedes, follows, or occurs in the same position as the other object.
`CompareTo(KeyValuePair<TKey,TValue> other)`	Compares the current instance with another `KeyValuePair<TKey,TValue>` of the same type and returns an integer that indicates whether the current instance precedes, follows, or occurs in the same position as the other object.
`Equals(object obj)`	Determines whether the specified object is equal to the current instance.
`Equals(KeyValuePair<TKey,TValue> other)`	Determines whether the specified `KeyValuePair<TKey,TValue>` is equal to the current instance.
`GetHashCode()`	Returns the hash code for the current instance.
`ToString()`	Returns a string representation of the `KeyValuePair<TKey,TValue>`.

Operators

Name	Description
`Equality (==)`	Compares two `KeyValuePair<TKey,TValue>` structures for equality.
`Inequality (!=)`	Compares two `KeyValuePair<TKey,TValue>` structures for inequality.

Remarks

The KeyValuePair<TKey,TValue> structure is immutable. Once created, its Key and Value properties cannot be changed.

It is commonly used when iterating through a dictionary. For example:


using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        var cities = new Dictionary<string, string>()
        {
            { "UK", "London" },
            { "France", "Paris" },
            { "Japan", "Tokyo" }
        };

        foreach (KeyValuePair<string, string> kvp in cities)
        {
            Console.WriteLine($"Country: {kvp.Key}, Capital: {kvp.Value}");
        }
    }
}

Examples

Creating a KeyValuePair


var kvp = new KeyValuePair<int, string>(1, "Apple");
Console.WriteLine($"Key: {kvp.Key}, Value: {kvp.Value}");
// Output: Key: 1, Value: Apple

Using KeyValuePair in a Dictionary


var dictionary = new Dictionary<string, int>();
dictionary.Add("One", 1);
dictionary.Add("Two", 2);

foreach (var item in dictionary)
{
    Console.WriteLine($"Key: {item.Key}, Value: {item.Value}");
}
// Output:
// Key: One, Value: 1
// Key: Two, Value: 2