How to Throw Exceptions in C#: A Comprehensive Guide
Exception handling is one of the key features when developing robust applications in C#. Exceptions let you control the flow of a program at runtime by giving a structured way of handling errors that occur whenever things go wrong during the execution. In this blog, we will take you through how to throw exceptions in C#.
What is an Exception?
An exception is an error condition that interrupts the normal course of a program. C# uses exceptions to signal and handle errors using the try-catch-finally block and the throw keyword.
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How to Throw Exceptions in C#
Throwing an exception in C# is quite simple. You use the throw keyword followed by an instance of an exception class. Here is the basic syntax:
throw new Exception("An error occurred.");
Common Exception Classes in C#
System.Exception - Abstract class for all exceptions.
System.ArgumentException - The method arguments are invalid.
System.NullReferenceException- Null object references.
System.InvalidOperationException- Operations inapplicable.
System.IO.IOException- A file input/output error has arisen.
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Throwing Exceptions with Custom Messages
Custom error messages provide greater context when an exception is raised.
public void ValidateAge(int age)
{
if (age < 0)
{
throw new ArgumentOutOfRangeException(nameof(age), "Age cannot be negative.");
}
}
Best Practices in Throwing Exceptions
1. Avoid Exception Types to Use Specifics: Never throw the Exception type, unless in a subclass where it serves for a derived-class exception
2. Always throw informative messages- Explain how it went wrong.
3. Do Not throw exceptions at ordinary control-flow paths. Avoid exceptions altogether as a method to transfer flow
4. Wrap inner exceptions before rethrowing:
try {
// Do something
}catch (Exception ex)
{
throw new InvalidOperationException ("Operation failed.",ex);
Custom Exception Classes
You can create your custom exception classes by inheriting from Exception:
public class CustomException : Exception
{
public CustomException(string message) : base(message) { }
}
Usage:
throw new CustomException("Something went wrong.");
Rethrowing Exceptions
Use throw; to retain the original stack trace while rethrowing exceptions:
try
{
// Some operation
}
catch
{
throw; // Retains the original stack trace
}
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Conclusion
Throwing exceptions in C# is one of the most powerful ways to handle errors so that your application can respond graciously to unexpected conditions. Best practices and proper exception types make your code readable, maintainable, and easier to debug.
Are there any problems with exception handling in C#? Please do not hesitate to share your experience in the comments below!
