How Can I Efficiently Catch Multiple Exceptions in a Single Code Block?

Catch multiple exceptions in a single code block

In programming languages, catching exceptions is an important part of error handling. However, when multiple specific exceptions need to be caught, especially when performing multiple operations on an object, it can become verbose and repetitive.

Question:

Consider the following code where you try to parse a GUID from a query string and set it to a field:

<code>try
{
    WebId = new Guid(queryString["web"]);
}
catch (FormatException)
{
    WebId = Guid.Empty;
}
catch (OverflowException)
{
    WebId = Guid.Empty;
}</code>

In this example, if a FormatException or OverflowException occurs during GUID parsing, the WebId will be set to Guid.Empty. However, if any other unexpected exception is encountered, it will propagate without being handled. To avoid boilerplate code and handle multiple exceptions efficiently, a better solution is needed.

Solution: catch System.Exception and switch based on type

To catch multiple exceptions in a single block of code, you can use the catch (Exception ex) syntax. This will catch all exceptions inherited from the base Exception class, including specific exceptions such as FormatException and OverflowException.

After catching an exception, you can use a switch statement based on the type of exception to determine how to handle it. If the exception is a known exception (for example, FormatException or OverflowException), you can perform specific actions (for example, set the WebId to Guid.Empty). Otherwise, you can rethrow the exception to allow higher-level code to handle it.

<code>catch (Exception ex)            
{                
    if (ex is FormatException || ex is OverflowException)
    {
        WebId = Guid.Empty;
    }
    else
        throw;
}</code>

This approach allows you to catch multiple specific exceptions in a block of code and handle them as needed, while still allowing unexpected exceptions to propagate.

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