How to iterate over a dictionary in C#

A dictionary is a type of collection in C# that stores elements as key/value pairs. It does not maintain a specific order for its elements.

Syntax

Here is the syntax on how to define a dictionary in C#:

Dictionary<int, string> MyDict = new Dictionary<int, string>();

In the above example, the MyDict dictionary holds key-value pairs where the keys are of type int and the values are of type string.

Example

Let's now learn about how we can iterate over a dictionary in C# using the coding example below:

using System;
using System.Collections.Generic;
class MainClass {
  public static void Main (string[] args) {
    Dictionary<string, string> MyDict = new Dictionary<string, string>();
    MyDict.Add("key1", "value1");
    MyDict.Add("key2", "value2");
    MyDict.Add("key3", "value3");
    foreach (KeyValuePair<string, string> pair in MyDict) {
      Console.WriteLine("{0} = {1}", pair.Key, pair.Value);
    }
  }
}

Explanation

Let's now look at the explanation of the above coding example:

  • Line 6: We declare a new variable named MyDict and initialize it with a new instance of the Dictionary<string, string> class. This dictionary stores key-value pairs where both the keys and values are of type string.

  • Lines 7–9: We add a new key-value pair to the MyDict dictionary. In this example, key1, key2, and key3 are the keys of the MyDict dictionary and value1, value2, and value3 are the corresponding values to these keys, respectively.

  • Line 11: We write a foreach loop that iterates over each key-value pair in the MyDict dictionary. During each iteration, the current key-value pair is stored in the pair variable, which is of type KeyValuePair<string, string>.

  • Line 12: This line outputs the current key-value pair. It uses the Console.WriteLine method to format the output. The placeholders {0} and {1} are replaced with the values of the pair.Key and pair.Value, respectively. As a result, each key-value pair in the dictionary will be printed.

Here is the output of the above coding example:

key1 = value1
key2 = value2
key3 = value3

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