Catch Multiple Exceptions in C#

While creating any software, developers try to create application which doesn't stop by any application error, so they handle errors using Try/Catch block in C#, but usually in old C# code, we have to implement multiple catch for each exception, so in this article, I have mentioned how you can catch multiple exceptions in C# using one or single catch block.

Suppose we have some code and we have single try block with multiple catch exceptions, since the code inside try{} block can throw multiple exceptions, so it would look like below

try
{
  // Some Code which can throw multiple exceptions
}
catch (FormatException ex)
{
  // handle format exceptions
}
catch (OverflowException ex)
{
  // handle overflow exception
}
catch (DivideByZeroException)
{
  // handle divide by zero exception
}

But as you can see from above code structure, we have repeated code, so to avoid it, if you are using C# 6+, then you can simply use single catch block for multiple exceptions.

Take a look at an example code below

using System;

namespace MultipleCatchCsharp
{
    public class Program
    {
        static void  Main(string[] args)
        {
            try
            {
                var numerator = Convert.ToUInt32("12");
                var denominator = Convert.ToUInt32("0");
                var result = (int)(numerator / denominator);
                Console.WriteLine(result);
            }
            catch (Exception ex) when (ex is FormatException ||
                                       ex is DivideByZeroException ||
                                       ex is OverflowException)
            {
                Console.WriteLine("Error: " + ex.Message);
            }
        }

    }
}

output:

Error: Attempted to divide by zero.

In the above code, we are trying to divide by zero, after converting string into int in C# and exception "DivideByZeroException" occured.

let's try to update the code to get FormatException, it would look like below

 try
            {
                var numerator = Convert.ToUInt32("12");
                var denominator = Convert.ToUInt32("10d");
                var result = (int)(numerator / denominator);
                Console.WriteLine(result);
            }
            catch (Exception ex) when (ex is FormatException ||
                                       ex is DivideByZeroException ||
                                       ex is OverflowException)
            {
                Console.WriteLine("Error: " + ex.Message);
            }

and the output will be

Error: Input string was not in a correct format.

Since we are trying to convert decimal into int.

So from the above code example, we can see a single catch block can be used to handle multiple exceptions in C#.

Updating Format to get separate exception messages for each Exception

We can also use Switch case inside Catch block, to separate exceptions code, as shown below

using System;

namespace MultipleCatchCsharp
{
    public class Program
    {
        static void  Main(string[] args)
        {
            try
            {
                var numerator = Convert.ToUInt32("12");
                var denominator = Convert.ToUInt32("10d");
                var result = (int)(numerator / denominator);
                Console.WriteLine(result);
            }
            catch (Exception ex) 
            {
                switch (ex)
                {
                    case FormatException:
                        Console.WriteLine("Error: Format Exception");
                        break;
                    case DivideByZeroException:
                        Console.WriteLine("Error: Divide By Zero Exception");
                        break;
                    case OverflowException:
                        Console.WriteLine("Error: Overflow Exception");
                        break;
                }
                
            }
        }

    }
}

Output:

Error: Format Exception

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