How to iterate over a C# list?

A List in C# is a generic collection that stores elements of the same type. There are several ways to iterate over a C# list, each with its own advantages depending on your specific needs.

Syntax

Following is the basic syntax for declaring and initializing a list −

List<T> listName = new List<T>();

Following are the common iteration syntaxes −

// foreach loop
foreach(var item in list) {
   // process item
}

// for loop
for(int i = 0; i < list.Count; i++) {
   // process list[i]
}

Using foreach Loop

The foreach loop is the most common and readable way to iterate over a list. It automatically handles the iteration without requiring index management −

using System;
using System.Collections.Generic;

public class Demo {
   public static void Main(string[] args) {
      var products = new List<string>();
      products.Add("Belts");
      products.Add("T-Shirt");
      products.Add("Trousers");

      Console.WriteLine("Our list....");
      foreach(var p in products) {
         Console.WriteLine(p);
      }
   }
}

The output of the above code is −

Our list....
Belts
T-Shirt
Trousers

Using for Loop with Index

When you need access to the index of each element, use a traditional for loop −

using System;
using System.Collections.Generic;

public class Demo {
   public static void Main(string[] args) {
      var numbers = new List<int> {10, 20, 30, 40, 50};

      Console.WriteLine("List with indexes:");
      for(int i = 0; i < numbers.Count; i++) {
         Console.WriteLine("Index " + i + ": " + numbers[i]);
      }
   }
}

The output of the above code is −

List with indexes:
Index 0: 10
Index 1: 20
Index 2: 30
Index 3: 40
Index 4: 50

Using while Loop

A while loop can also be used for iteration, though it's less common −

using System;
using System.Collections.Generic;

public class Demo {
   public static void Main(string[] args) {
      var colors = new List<string> {"Red", "Green", "Blue"};
      
      int index = 0;
      Console.WriteLine("Colors using while loop:");
      while(index < colors.Count) {
         Console.WriteLine(colors[index]);
         index++;
      }
   }
}

The output of the above code is −

Colors using while loop:
Red
Green
Blue

Comparison of Iteration Methods

Conclusion

The foreach loop is the preferred method for simple list iteration in C# due to its clean syntax and safety. Use for loops when you need index access, and while loops for more complex iteration scenarios.