Csharp-tips on Code4IT

C# Tip: How to JSON Serialize and Deserialize values as DateTime, DateTimeOffset, DateOnly and TimeOnly

Tue, 24 Mar 2026 00:00:00 +0000

Handling dates is never trivial. And handling JSON serialization and deserialization of dates is even more difficult. And, even worse, how can you convert a value as DateTime, DateTimeOffset, DateOnly and TimeOnly?

[C# Tip] How to create and access custom C# Attributes by using Reflection

Tue, 16 Dec 2025 00:00:00 +0000

In C#, Attributes are a handy mechanism to attach metadata to your classes, methods, properties, etc. In this article, we will see how to create custom Attributes and access them at runtime using Reflection.

C# Tip: injecting and testing the current time with TimeProvider and FakeTimeProvider

Tue, 02 Sep 2025 00:00:00 +0000

Dates used to be difficult to test. But with TimeProvider and FakeTimeProvider, everything becomes possible!

C# Tip: Handling exceptions with Task.WaitAll and Task.WhenAll

Tue, 10 Jun 2025 00:00:00 +0000

Task.WhenAll and Task.WaitAll are common methods in C# that allow you to execute multiple Tasks. But… what happens when an exception is thrown?

C# Tip: An In-Depth Look at CallerMemberName (and some Compile-Time trivia)

Tue, 25 Mar 2025 00:00:00 +0000

Let’s dive deep into the CallerMemberName attribute and explore its usage from multiple angles. We’ll see various methods of invoking it, shedding light on how it is defined at compile time.

C# Tip: How to create Custom Attributes, and why they are useful

Tue, 21 Jan 2025 00:00:00 +0000

Applying custom attributes to C# classes and interfaces can be useful for several reasons. Let’s learn how to create Custom Attributes in C#, and let’s explore some practical usage!

C# Tip: 2 ways to generate realistic data using Bogus

Tue, 03 Dec 2024 00:00:00 +0000

Bogus is a library that generates realistic values for your data. When populating fake user names, instead of Foo and Bar, you can have John and Sarah. Let’s see two ways to define and reuse a Faker definition.

C# Tip: IEnumerable vs ICollection, and why it matters

Tue, 15 Oct 2024 00:00:00 +0000

When working with Lists in C#, you are working on a data structure that implements both ICollection and IEnumerable. What’s the difference between ICollection and IEnumerable? Why should you care about them, especially when exposing functionalities to external clients?

C# Tip: 2 ways to use custom equality rules in a HashSet

Tue, 27 Aug 2024 00:00:00 +0000

With HashSet, you can get a list of different items in a performant way. What if you need a custom way to define when two objects are equal?

C# Tip: Mark a class as Sealed to prevent subclasses creation

Tue, 16 Jul 2024 00:00:00 +0000

The sealed keyword is often ignored, yet it can be important to define a proper class design.

C# Tip: Path.Combine and Path.Join are similar but way different.

Tue, 25 Jun 2024 00:00:00 +0000

When composing the path to a folder or file location, the Path class can come in handy. Path.Join and Path.Combine may look similar, but their behavior differ in an unexpected way.

C# Tip: IFormattable interface, to define different string formats for the same object

Tue, 27 Feb 2024 00:00:00 +0000

Same object, different string representations. How do we achieve it in a standardised way?

C# Tip: ObservableCollection - a data type to intercept changes to the collection

Tue, 23 Jan 2024 00:00:00 +0000

ObservableCollection<T> is a data type that allows you to react when an item is added or removed from the collection. Let’s learn more!

C# Tip: Use TestCase to run similar unit tests with NUnit

Tue, 28 Nov 2023 00:00:00 +0000

Learn how to organize similar unit tests using the TestCase attribute in NUnit!

C# Tip: How to create Unit Tests for Model Validation

Tue, 24 Oct 2023 00:00:00 +0000

As you know, you should always validate input models. Therefore, you should create Unit Tests to test the data validation. Let’s learn!

C# Tip: Improve memory allocation by initializing collection size

Tue, 26 Sep 2023 00:00:00 +0000

Sometimes just a minor change can affect performance. Here’s a simple trick: initialize your collections by specifying the initial size!

C# Tip: 2 ways to define ASP.NET Core custom Middleware

Tue, 11 Jul 2023 00:00:00 +0000

Customizing the behavior of an HTTP request is easy: you can use a middleware defined as a delegate or as a class.

C# Tip: Use custom Equality comparers in Nunit tests

Tue, 13 Jun 2023 00:00:00 +0000

When writing unit tests, there are smarter ways to check if two objects are equal than just comparing every field one by one.

C# Tip: Advanced Switch Expressions and Switch Statements using filters

Tue, 16 May 2023 00:00:00 +0000

We all use switch statements in our code. Do you use them at their full potential?

C# Tip: Format Interpolated Strings

Tue, 02 May 2023 00:00:00 +0000

Interpolated strings are those built with the $ symbol, that you can use to create strings using existing variables or properties. Did you know that you can apply custom formattings to such values?

C# Tip: Access items from the end of the array using the ^ operator

Tue, 11 Apr 2023 00:00:00 +0000

Shorter code is often easier to read. Not always, but often. And the ^ operator can make your code easier to read and less error-prone

C# Tip: Initialize lists size to improve performance

Tue, 28 Feb 2023 00:00:00 +0000

Lists have an inner capacity. Every time you add more items than the current Capacity, you add performance overhead. How to prevent it?

C# Tip: List Pattern to match an collection against a sequence of patterns

Tue, 14 Feb 2023 00:00:00 +0000

By using list patterns on an array or a list you can check whether a it contains the values you expect in a specific position.

C# Tip: do NOT use nameof to give constants a value

Tue, 31 Jan 2023 00:00:00 +0000

In C#, nameof can be quite useful. But it has some drawbacks, if used the wrong way.

C# Tip: LINQ's Enumerable.Range to generate a sequence of consecutive numbers

Tue, 17 Jan 2023 00:00:00 +0000

If you need a sequence of numbers, you can pick two ways: use a While loop, or use Enumerable.Range

C# Tip: Raise synchronous events using Timer (and not a While loop)

Tue, 29 Nov 2022 00:00:00 +0000

When you need to fire synchronous events, don’t use a while(true) loop: use a Timer!

C# Tip: use the @ prefix when a name is reserved

Tue, 25 Oct 2022 00:00:00 +0000

C#, as every other language, has several reserved keywords. Did you know that you can use them if you use the @ prefix?

C# Tip: use Miniprofiler instead of Stopwatch to profile code performance

Tue, 13 Sep 2022 00:00:00 +0000

Miniprofiler is a nice tool to profile your code in a smart way.

C# Tip: SelectMany in LINQ

Tue, 12 Jul 2022 00:00:00 +0000

SelectMany is one of the LINQ methods I’ve used the least. I couldn’t get it! Turns out it was actually incredibly simple.

C# Tip: use IHttpClientFactory to generate HttpClient instances

Tue, 07 Jun 2022 00:00:00 +0000

Initializing HttpClient instances can expose you to Socket Exhaustion problems. You should use IHttpClientFactory instead

C# Tip: Convert ExpandoObjects to IDictionary

Tue, 10 May 2022 00:00:00 +0000

How to get all the keys of an ExpandoObject? Convert it to Dictionary!

C# Tip: Use Debug-Assert to break the debugging flow if a condition fails

Tue, 05 Apr 2022 00:00:00 +0000

It would be great if we could break the debugging flow if a condition is (not) met. Can we? Of course!

C# Tip: How to temporarily change the CurrentCulture

Tue, 08 Mar 2022 00:00:00 +0000

What can you do if you need to temporarily change the CurrentCulture in C#?

C# Tip: Exception handling with WHEN clause

Tue, 08 Feb 2022 00:00:00 +0000

Instead of using if-else or switch blocks to handle exceptions, you can do it gracefully using the ‘when’ keyword.

C# Tip: use yield return to return one item at the time

Tue, 14 Dec 2021 00:00:00 +0000

Yield is a keyword that allows you to return an item at the time instead of creating a full list and returning it as a whole.

C# Tip: Use a SortedSet to avoid duplicates and sort items

Tue, 16 Nov 2021 00:00:00 +0000

Using the right data structure is crucial to building robust and efficient applications. So, why use a List or a HashSet to sort items (and remove duplicates) when you have a SortedSet?

C# Tip: use the Ping class instead of an HttpClient to ping an endpoint

Tue, 19 Oct 2021 00:00:00 +0000

Sometimes you need to ping some endpoints. Don’t rely on HttpClient, but use the native Ping class.

C# tip: define Using Aliases to avoid ambiguity

Tue, 21 Sep 2021 00:00:00 +0000

Sometimes we need to use objects with the same name but from different namespaces. How to remove that ambiguity? By Using Aliases!

C# tip: create correct DateTimes with DateTimeKind

Sat, 07 Aug 2021 00:00:00 +0000

Creating simple DateTimes creates issues when handling timezones. You can solve some issues by using DateTimeKind

C# tip: String.IsNullOrEmpty or String.IsNullOrWhiteSpace?

Tue, 06 Jul 2021 00:00:00 +0000

Is your string really empty, or has it hidden characters? With String.IsNullOrEmpty and String.IsNullOrWhiteSpace you can find it

C# tip: how to get the index of an item in a foreach loop

Tue, 08 Jun 2021 00:00:00 +0000

Do you need the index of the current item in a foreach loop with C#? Here you’ll see two approaches.