Check out all the C#.Net tutorials.
For a C# LINQ group by, call GroupBy with a key selector such as s => s.State. You get one group per key, and each group carries its Key plus its items, so Count() and Sum() work per group: Below, the same eight US sales get grouped by two columns, filtered like SQL HAVING, turned … Read more >>
The most common mistake when a team turns on C# nullable reference types is silencing every warning with the ! operator. The build goes quiet, but the app still crashes, because ! only hides the warning: Quick answer: keep <Nullable>enable</Nullable> on, mark values that can be missing as string?, and fix each warning with a … Read more >>
Say you’re writing shipping rules for an online outdoor store. Orders of $100 or more ship free, Alaska and Hawaii pay $24.99, and anything over 50 pounds goes freight. C# pattern matching tests a value’s type, ranges and properties in one expression with is or a switch expression, and the compiler warns you about cases … Read more >>
To make a C# HttpClient call, create one shared HttpClient with a BaseAddress, then call GetFromJsonAsync<T>. It sends the GET request and turns the JSON response into a typed object: Every example below ran on .NET 10 against a small orders API I started on localhost, from POST and headers to timeouts, IHttpClientFactory and automatic … Read more >>
If you’re modeling a shipping address or an API payload, here’s my rule for C# record vs class: use a record when two objects with the same values should be equal. Use a class for objects with identity and changing state, and a struct only for tiny values. I ran all three on one Austin, … Read more >>
To turn a C# object into JSON with System.Text.Json, call JsonSerializer.Serialize; to read it back, call JsonSerializer.Deserialize<T>. Both live in the System.Text.Json namespace that ships with .NET: I ran every example below on .NET 10 against one US customer order, including the native AOT default that breaks reflection JSON in file-based apps. The Sample Order … Read more >>
Say you’re building a shipping-quote screen for a Dallas warehouse. It asks UPS, FedEx and USPS for a rate one after another, and each API takes a second, so every quote takes 3 seconds. That’s the job of the async await C# pattern: await frees the thread while a call waits, and Task.WhenAll lets all … Read more >>
Since .NET 10, you can run a C# file with no project at all. Type dotnet run file.cs (here, dotnet run app.cs) and the SDK builds and runs that one file. This three-line app.cs is the whole program: Output of dotnet run app.cs: I tested everything below on Windows 11 with SDK 10.0.402: NuGet packages, … Read more >>
To use LINQ in C#, you call query methods such as Where, Select and OrderBy on any array or list, and pass each one a small lambda that says what to keep, pick or sort by: I ran the queries below on .NET 10 against one list of six US orders, including the new LeftJoin … Read more >>
Open a terminal and type dotnet –version. That’s the quickest way to check the .NET version, and it prints the SDK the CLI will use right here. dotnet –list-sdks and dotnet –list-runtimes show everything else that’s installed. In this tutorial, I’ll list the places where I check .NET version details on a real machine: the … Read more >>