How to iterate over a dictionary in C#?

In C#, there are several ways to iterate over a dictionary. Here are a few examples:

#1 Using a foreach loop

Dictionary<string, int> dict = new Dictionary<string, int>();
dict.Add("apple", 1);
dict.Add("banana", 2);
dict.Add("cherry", 3);

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

In this example, we define a Dictionary<string, int> and add some key-value pairs to it. We then use a foreach loop to iterate over the dictionary and print out each key-value pair.

#2 Using a for loop and the KeyValuePair struct

Dictionary<string, int> dict = new Dictionary<string, int>();
dict.Add("apple", 1);
dict.Add("banana", 2);
dict.Add("cherry", 3);

for (int i = 0; i < dict.Count; i++)
{
    KeyValuePair<string, int> kvp = dict.ElementAt(i);
    Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
}

In this example, we define a Dictionary<string, int> and add some key-value pairs to it. We then use a for loop to iterate over the dictionary by index. Inside the loop, we use the ElementAt method to get the key-value pair at the current index and print out its key and value.

#3 Using a foreach loop with the Keys or Values property

Dictionary<string, int> dict = new Dictionary<string, int>();
dict.Add("apple", 1);
dict.Add("banana", 2);
dict.Add("cherry", 3);

foreach (string key in dict.Keys)
{
    Console.WriteLine("Key = {0}, Value = {1}", key, dict[key]);
}

foreach (int value in dict.Values)
{
    Console.WriteLine("Value = {0}", value);
}

In this example, we define a Dictionary<string, int> and add some key-value pairs to it. We then use two foreach loops to iterate over the dictionary. The first loop uses the Keys property to iterate over the keys, and the second loop uses the Values property to iterate over the values. Inside each loop, we print out the current key or value.

All of these methods will produce the same output:

Key = apple, Value = 1
Key = banana, Value = 2
Key = cherry, Value = 3
Value = 1
Value = 2
Value = 3

The method you choose will depend on your specific use case and personal preference. In general, the foreach loop is the simplest and most commonly used method for iterating over a dictionary in C#.