CodeUtility
Making your developer's life easier!

Online C# Compiler & Debugger

Write, compile, run, and debug C# code online. Set breakpoints, step into or over code, and inspect variables and nested objects in a full IDE with multiple files, saved workspaces, sharing, and live collaboration—no setup required.

Pre-installed Libs
🚀 349,496 total executions (43,754 this month)
Output

Practice C# with coding challenges

Solve hands-on problems right in this editor: run the sample tests, submit, and get an AI code review.

All C# challenges
Easy

Average of Three

Average three whole numbers.

BeginnerLearning-pathVariables
Python C++ C#
1 solved
View solutions (1)
Easy

Rectangle Perimeter

Compute the perimeter of a rectangle from its sides.

BeginnerLearning-pathVariables
Python C++ C#
1 solved
View solutions (1)
Hard

Course Schedule Order

Order courses so every prerequisite comes first.

AdvancedGraphsHackathonTopological-sort
Python C++ C#
0 solved
No solutions yet
Medium

Island Perimeter

Measure the coastline of land cells in a grid.

AdvancedGridsHackathon
Python C++ C#
0 solved
No solutions yet
Medium

K-th Smallest Element

Find the k-th smallest value without fully sorting.

AdvancedCompetitive-programmingSorting
Python C++ C#
0 solved
No solutions yet
Hard

Median of Two Sorted Arrays

Find the median of two sorted lists combined.

AdvancedBinary-searchCompetitive-programming
Python C++ C#
0 solved
No solutions yet
Medium

Game of Life Step

Advance Conway's Game of Life by one generation.

AdvancedGridsHackathonSimulation
Python C++ C#
0 solved
No solutions yet
Hard

Shortest Delivery Tour

Visit every city once and return home as cheaply as possible.

AdvancedBitmasksCompetitive-programmingDynamic-programming
Python C++ C#
0 solved
No solutions yet
Hard

Strongly Connected Components

Count groups of nodes that can all reach each other.

AdvancedCompetitive-programmingGraphs
Python C++ C#
0 solved
No solutions yet
Hard

Longest Path in a DAG

Find the heaviest path in a task dependency graph.

AdvancedGraphsHackathonTopological-sort
Python C++ C#
0 solved
No solutions yet
Hard

Matrix Chain Multiplication

Find the cheapest order to multiply a chain of matrices.

AdvancedCompetitive-programmingDynamic-programming
Python C++ C#
0 solved
No solutions yet
Hard

Minimum Window Substring

Find the shortest piece of text containing all required characters.

AdvancedCompetitive-programmingSliding-windowStrings
Python C++ C#
0 solved
No solutions yet

🔷 About This C# / .NET Online Executor

The CodeUtility C# Executor lets you write and run real C# code directly in your browser - no installation, Visual Studio setup, or .NET SDK required. It’s powered by a secure sandbox that supports the .NET runtime and modern C# language versions, including C# 9 and later.

This tool uses dotnet-script under the hood to compile and execute your code with true .NET behavior, allowing you to experiment with both basic and advanced C# features like LINQ, async/await, pattern matching, and generics.

You can test simple scripts, functions, and logic flows, or explore concepts like classes, structs, inheritance, and interfaces - all in a clean, distraction-free coding environment.

Whether you’re learning C#, testing algorithms, or experimenting with .NET features, the CodeUtility C# Executor gives you a fast, secure, and reliable way to run C# code instantly from any browser.

More than a code runner

Use a multi-file editor, an isolated execution terminal, runtime-specific libraries, persistent workspaces, sharing, and real-time collaboration from the same executor.

How to use this executor?

Choose a runtime, open or create a file, write your code, and select Run. Output appears in the terminal, while signed-in users can keep files in a workspace, install libraries, and collaborate through shares.

  1. Select a version and edit the current file or open another workspace file.
  2. Run the code, provide input in the terminal when requested, and review saved run history.
  3. Use libraries, workspace tools, sharing, and chat when your task needs more than one snippet.

💡 C# Basics & Examples You Can Try Above

1. Declaring Variables and Constants

C# uses strongly-typed variable declarations. Use const for compile-time constants and readonly for runtime constants. 

int age = 30;
double pi = 3.14159;
char grade = 'A';
string name = "Alice";
bool isActive = true;

// Constants
const int MaxUsers = 100;
const string Company = "CodeUtility";

2. Conditionals (if / switch)

Use if, else if, and switch for control flow.

int x = 2;
if (x == 1)
{
    Console.WriteLine("One");
}
else if (x == 2)
{
    Console.WriteLine("Two");
}
else
{
    Console.WriteLine("Other");
}

switch (x)
{
    case 1:
        Console.WriteLine("One");
        break;
    case 2:
        Console.WriteLine("Two");
        break;
    default:
        Console.WriteLine("Other");
        break;
}

3. Loops

C# supports for, while, and foreach loops.

for (int i = 0; i < 3; i++)
{
    Console.WriteLine(i);
}

int n = 3;
while (n > 0)
{
    Console.WriteLine(n);
    n--;
}

4. Arrays

Arrays store fixed-size collections of elements of the same type.

int[] numbers = { 10, 20, 30 };
Console.WriteLine(numbers[1]);

5. List Manipulation

Use List<T> for dynamic collections.

List<int> nums = new List<int> { 1, 2, 3 };
nums.Add(4);
nums.Remove(2);

foreach (int n in nums)
{
    Console.Write(n + " ");
}

6. Console Input/Output

Use Console.WriteLine and Console.ReadLine for basic I/O.

Console.Write("Enter your name: ");
string name = Console.ReadLine();
Console.WriteLine($"Hello, {name}!");

7. Functions

Define methods using a return type, name, and parameters.

int Add(int a, int b)
{
    return a + b;
}

Console.WriteLine(Add(3, 4));

8. Dictionaries

Dictionary<TKey, TValue> stores key-value pairs.

Dictionary<string, int> ages = new Dictionary<string, int>();
ages["Alice"] = 30;
Console.WriteLine(ages["Alice"]);

9. Exception Handling

Handle runtime errors using try, catch, and finally.

try
{
    throw new Exception("Something went wrong");
}
catch (Exception ex)
{
    Console.WriteLine(ex.Message);
}

10. File I/O

Use File and StreamReader/StreamWriter for file operations.

File.WriteAllText("file.txt", "Hello File");
string text = File.ReadAllText("file.txt");
Console.WriteLine(text);

11. String Manipulation

C# strings support methods like Length, Substring, Contains.

string message = "Hello World";
Console.WriteLine(message.Length);
Console.WriteLine(message.Substring(0, 5));
Console.WriteLine(message.Contains("World"));

12. Classes & Objects

C# supports object-oriented programming through classes and objects.

class Person
{
    public string Name;
    public Person(string name) => Name = name;
    public void Greet() => Console.WriteLine($"Hi, I'm {Name}");
}

Person p = new Person("Alice");
p.Greet();