The journey of every round

Use string.Split to break a CSV line into fields.

Read an environment variable using Environment.GetEnvironmentVariable.

Write an if/else that returns one string for even numbers and another for odd numbers.

Use async/await to read a file with File.ReadAllTextAsync.

Iterate over a Dictionary<string, int> and print each key-value pair.

Use a switch expression to map an enum value to a string.

Throw an ArgumentNullException if a parameter is null.

Write a method that returns Task<int> and uses await Task.Delay.

Use string interpolation to format a name and age into a sentence.

Write a Web API POST endpoint that accepts a JSON body and returns Created.

Open a SqlConnection, run a SELECT query, and read rows.

Write a LINQ Select that maps a list of strings to their lengths.

Write a basic dependency injection registration with services.AddScoped.

Read all lines from a text file using File.ReadAllLines.

Concatenate two strings and trim whitespace.

Read a configuration value from appsettings.json using IConfiguration.

Implement async/await with HttpClient.GetAsync and read the response body as JSON.

Show the basic structure of an ASP.NET Core controller with one GET endpoint.

Add a try/catch around a database call that logs the exception and returns a 500.

Configure OpenIdConnectOptions with pushed authorization requests and a custom IClaimsTransformation that enriches the principal with role data.

Implement IExceptionHandler (the .NET 8 abstraction) that maps domain exceptions to ProblemDetails with trace_id from Activity.Current.

Implement IRequestPostProcessor<TRequest, TResponse> in MediatR to log every successful response with structured ILogger<T> properties.

Add a fallback resilience pipeline using ResiliencePipeline.AddFallback that swaps to a cached IDistributedCache value on inner failure.

Use Keyed services (Microsoft.Extensions.DependencyInjection 8.0) to register multiple implementations of an interface and resolve by string key.