Suppressed Exception On The Empty Catch Block

When you investigate an issue or a problem you usually get the error or exception message first and then try to replicate that exception in a lower environment such as your local machine. What if there was an error but the application did not produced a message or even a trace where the error occurred? Big problem. One such case to avoid this problem and to avoid passing this problem to the next person that will support your application, is to avoid having suppressed exception on the empty catch block on your code. Yes, having an empty catch block will not be detected by the C# compiler, bummer.

The culprit

public class SilentExceptionSample
{

public void DivideOperation(int a, int b)
{
try
{
var result = a / b;
}
catch (Exception)
{
//throw;
}

}

}

The code above is a sample method that does not return anything (void) and an operation to divide a and b. A try catch block will be able to catch any exception that may happen but throwing the exception that may happen is a different scenario. Inside the catch block, the C# compiler allows the block to be empty and not return anything. Most of the time this block can contain a logic to handle the exception such as logging and external error handlers. What happens if the developer leaves the block empty without the intention of leaving it empty? Errors in your application will not have any trace.

Some unit testing

[TestFixture]
public class SuppressedExceptions
{

[Test]
public void Division_With_Exception_Test() {

var silentException = new SilentExceptionSample();

Assert.Throws(() => silentException.DivideOperation(1,0));
}

[Test]
public void Division_With_NoException_Test()
{
var silentException = new SilentExceptionSample();

Assert.DoesNotThrow(() => silentException.DivideOperation(1,1));
}

}

I created a unit test to test the exception, on this sample above its the DivideByZeroException, that the method will throw when you divide a number by zero. The test fails in the first scenario since the error suppressed exception on the empty catch block.

Test Results

Ways to avoid

There can be ways to avoid this code smell. I suggest the following…

Unit Test

– Perform unit tests on exception handling on your code.

Code Snippet

– Use the code snippets on Visual Studio. If you want to use a try catch block, typing in “try” then tab will auto complete the whole block.

Resharper

– Tools such as Resharper can help in detecting code smells. See the warning below from the Resharper engine on the empty catch block.
Resharper Warning

This type of code smell can be the source of problem you are investigating now or something you can prevent while in development. You’ve been warned! ๐Ÿ™‚

Comparing using CompareTo C# Method

 

A colleague asked me for a suggestion on the program module he is doing that involves determining if one value is “>” greater than, “=” equal or “<” less than another value. I first thought of a solution involving a stack but its too low level and involves much longer code. After some suggestions and trying to think of another way, he came across of a solution to use CompareTo C# method.

What is CompareTo C# Method?

First, MSDN defines IComparable as an interface that “Defines a generalized type-specific comparison method that a value type or class implements to order or sort its instances.” It has a method called CompareTo which as defined by MSDN “Compares the current instance with another object of the same type and returns an integer that indicates whether the current instance precedes, follows, or occurs in the same position in the sort order as the other object.”

The CompareTo method is available on all objects as long as the objects has the same type. See the sample code below for comparing value types integer and a string type.

CsharpCompareTo

 

The Return Value of CompareTo

The CompareTo method has a return value of int. The integer value return will be one of the values less than 0, 0 or greater than zero as what is shown below.

CompareToReturnValues

 

Nullable Types Does Not Implement CompareTo

Take note that Nullable types like int? short for Nullable<int> does not implement the CompareTo method. It will not even compile since the method is not implemented.

CompareToNullable

This blog post will serve as a quick reference for me whenever there is a need for me to use sorting or comparison of data when programming. I hope it will serve the same for you.