BSc IT - Web Application Development - ASP.NET

Structured Exception Handling is a way to handle runtime errors in a controlled manner using predefined blocks

It prevents the application from crashing and allows you to manage errors gracefully.

Blocks:

• try : Contains code that might cause an error.
• catch : Handles the error if one occurs.
• finally : (Optional) Executes always — for cleanup (e.g., closing files, connections).

Example (C# in ASP.NET):

try
{
    int num1 = int.Parse(txtNumber1.Text);
    int num2 = int.Parse(txtNumber2.Text);
    int result = num1 / num2;
    lblResult.Text = "Result: " + result;
}
catch (FormatException)
{
    lblResult.Text = "Please enter valid numbers.";
}
catch (DivideByZeroException)
{
    lblResult.Text = "Cannot divide by zero.";
}
catch (Exception ex)
{
    lblResult.Text = "An error occurred: " + ex.Message;
}
finally
{
    // This runs no matter what
    txtNumber1.Text = "";
    txtNumber2.Text = "";
}

• Prevents app crashes on errors.
• Helps identify and handle different types of exceptions.
• Ensures resources are cleaned up properly.