C# Academy · Lesson

break/continue; goto (avoid); scope; exceptions vs guard checks

Use break and continue correctly, understand why goto is discouraged, apply scope rules safely, and choose between exceptions and guard checks.

break/continue; goto (avoid); scope; exceptions vs guard checks is a free C# Academy lesson on CoddyKit — lesson 2 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C# Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Lesson overview

Goal: Control loop flow with break/continue, avoid goto, respect variable scope, and pick between exceptions and guard checks.

break in action

break exits the loop immediately.

using System;

public class Program
{
  public static void Main(string[] args)
  {
    for (int i = 1; i <= 10; i = i + 1)
    {
      if (i == 4)
      {
        Console.WriteLine("Stop at 4");
        break; // exit loop completely
      }
      Console.WriteLine("i = " + i);
    }
  }
}

continue in action

continue skips the current iteration and goes to the next.

using System;

public class Program
{
  public static void Main(string[] args)
  {
    for (int i = 1; i <= 5; i = i + 1)
    {
      if (i % 2 == 0)
      {
        continue; // skip even numbers
      }
      Console.WriteLine("Odd: " + i);
    }
  }
}

Avoiding goto

goto creates spaghetti flow; use structured loops instead (while/for/foreach).

using System;

public class Program
{
  public static void Main(string[] args)
  {
    // Goto works but harms readability; prefer structured loops.
    int i = 0;
start:
    i = i + 1;
    Console.WriteLine("i = " + i);
    if (i < 3)
    {
      goto start; // avoid using goto in real code
    }

    // Prefer: while loop (clear intent)
    int j = 0;
    while (j < 3)
    {
      j = j + 1;
      Console.WriteLine("j = " + j);
    }
  }
}

Scope basics

Scope is defined by braces { }. Declare variables close to use and avoid name reuse in nested blocks.

using System;

public class Program
{
  public static void Main(string[] args)
  {
    int x = 10; // outer scope
    if (x > 0)
    {
      int y = 5; // inner scope
      Console.WriteLine("x + y = " + (x + y));
    }
    // y is not visible here; this would not compile:
    // Console.WriteLine(y);

    // Shadowing (avoid reusing names in nested scopes)
    int value = 1;
    {
      int valueInner = 2; // use a new name instead of shadowing
      Console.WriteLine("value=" + value + ", inner=" + valueInner);
    }
  }
}

Diagnostics basics

Use guard checks for expected invalid input; use exceptions for exceptional states.

using System;

public class Program
{
  // Guard check: return a bool and an out parameter (no exception on normal invalid input).
  public static bool TryDivide(int x, int y, out int result)
  {
    if (y == 0)
    {
      result = 0;
      return false; // guard fail
    }
    result = x / y;
    return true;
  }

  // Exceptional state: throw when something truly exceptional happens.
  public static int PriceWithTax(int price, int ratePercent)
  {
    if (price < 0)
    {
      throw new ArgumentOutOfRangeException("price");
    }
    if (ratePercent < 0 || ratePercent > 100)
    {
      throw new ArgumentOutOfRangeException("ratePercent");
    }
    return price + (price * ratePercent / 100);
  }

  public static void Main(string[] args)
  {
    int r;
    bool ok = TryDivide(10, 0, out r);
    Console.WriteLine("TryDivide ok=" + ok + " result=" + r);

    try
    {
      int total = PriceWithTax(100, 18);
      Console.WriteLine("Total=" + total);
    }
    catch (Exception ex)
    {
      Console.WriteLine("Error: " + ex.Message);
    }
  }
}

break vs continue

Quick check: What is the difference between break and continue in a loop?

Recap

Recap: Use break to exit and continue to skip an iteration; avoid goto; keep variables in the right scope; prefer guard checks for expected invalid input and exceptions for exceptional states.

Frequently asked questions

Is the “break/continue; goto (avoid); scope; exceptions vs guard checks” lesson free?

Yes — the full text of “break/continue; goto (avoid); scope; exceptions vs guard checks” is free to read here on the web, and the C# Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C# Academy course, upgrade to CoddyKit PRO.

What will I learn in “break/continue; goto (avoid); scope; exceptions vs guard checks”?

Use break and continue correctly, understand why goto is discouraged, apply scope rules safely, and choose between exceptions and guard checks. You practise C# Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C# Academy?

No prior experience is required. C# Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 3, so you can start here or from the beginning and move at your own pace.

How long does the “break/continue; goto (avoid); scope; exceptions vs guard checks” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C# Academy lesson?

Yes. Every C# Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

if/else, switch (classic), loops: for, while, do, foreach
break/continue; goto (avoid); scope; exceptions vs guard checks
Simple diagnostics: exceptions vs guard checks

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