Error Handling in C#

Error handling in C# is essential for building robust and reliable programs.
The language provides mechanisms to detect, catch, and respond to unexpected situations using exceptions.

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Using try-catch

The try-catch structure allows executing code that might fail and handling the exception in case of an error.

try
{
    int number = 10;
    int result = number / 0; // Error: division by zero
}
catch (DivideByZeroException ex)
{
    Console.WriteLine("Cannot divide by zero.");
    Console.WriteLine($"Details: {ex.Message}");
}

try-catch Flow

1. The try block contains the code that may produce an error.
2. The catch block catches and handles the exception.
3. Optionally, you can use finally to execute code regardless of whether an error occurred:

try
{
    Console.WriteLine("Trying to open resource...");
}
catch (Exception ex)
{
    Console.WriteLine($"An error occurred: {ex.Message}");
}
finally
{
    Console.WriteLine("Releasing resources...");
}

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Common Exceptions in C#

C# provides different exception classes that inherit from System.Exception.

1. System.Exception

This is the base class for all exceptions. It can be caught to handle any generic error.

try
{
    throw new Exception("Generic error.");
}
catch (Exception ex)
{
    Console.WriteLine($"Exception caught: {ex.Message}");
}

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2. System.NullReferenceException

Occurs when attempting to access an object that is null.

string text = null;
try
{
    Console.WriteLine(text.Length); // Error: null object
}
catch (NullReferenceException ex)
{
    Console.WriteLine("Null reference detected.");
}

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3. System.IndexOutOfRangeException

Happens when trying to access an index that doesn't exist in an array or collection.

int[] numbers = { 1, 2, 3 };
try
{
    Console.WriteLine(numbers[5]); // Error: index out of range
}
catch (IndexOutOfRangeException ex)
{
    Console.WriteLine("Index out of range.");
}

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4. System.DivideByZeroException

Appears when attempting to divide a number by zero.

try
{
    int result = 10 / 0;
}
catch (DivideByZeroException ex)
{
    Console.WriteLine("Error: division by zero.");
}

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Best Practices in Error Handling

• Catch only the necessary exceptions (avoid always using Exception).
• Use descriptive messages to understand the error.
• Release resources in the finally block or with using.
• Avoid silencing exceptions without handling them.