C# – Use yield return to minimize memory usage

Let’s say you want to search through a large text file for specific characters and return a list of context objects to the calling code for further processing (such as showing the results in the UI). One way to do that is to build the entire list at once and return it. If you don’t … Read more

C# – Save a list of strings to a file

The simplest way to save a list of strings to a file is to use File.WriteAllLines(). This creates (or overwrites) the specified file and writes each string on a new line. The resulting file looks like this: Note: Showing non-printable newline characters \r\n for clarity. Specifying the separator character What if you want to separate … Read more

C# – Remove non-alphanumeric characters from a string

The simplest way to remove non-alphanumeric characters from a string is to use regex: Note: Don’t pass in a null, otherwise you’ll get an exception. Regex is the simplest approach for solving this problem, but it’s also the slowest. If you’re concerned about the performance take a look at the performance section below. This example … Read more

C# – Convert a list to a dictionary

The simplest way to convert a list to a dictionary is to use the Linq ToDictionary() method: This loops through the list and uses the key/element selector lambdas you passed in to build the dictionary. In this article, I’ll go into details about how to use ToDictionary() and show how to deal with duplicate keys. … Read more

Get SQL Server query results as JSON

The simplest way to get query results as JSON is to use FOR JSON PATH in the query (note: this was added in SQL Server 2016): It returns the results as a single JSON string with one JSON object per row: Note: SQL Server returns the JSON without indenting. All examples in this article show … Read more

C# – Select distinct objects based on a property

There are three ways to select distinct objects based on a property using Linq: These select one movie per year: GroupBy() is the simplest because it doesn’t require any additional code. Distinct() is faster but it’s more complicated. DistinctBy() is the fastest and simplest, but requires the most code (it requires .NET 6 or getting … Read more

Comparing performance with Benchmark.NET graphs

The following graph compares the execution time of three sort implementations ran against varying input sizes (1k, 10k, 100k): This graph was generated using Benchmark.NET, which I’ll show how to use in this article. I’ll be comparing the performance of multithreaded quicksort implementations (with the non-threaded Array.Sort() as a baseline). Create console app and reference … Read more

C# – Pad a 2D array on all sides

Padding a 2D array on all sides means adding new rows on the top and bottom, new columns on the left and right, and then copying the original elements to the center of the padded array. It looks like this: There are two approaches for copying the elements. You can either copy individual items in … Read more

C# – How to use table-valued parameters (TVP) with ADO.NET, Dapper, and EF Core

Table-valued parameters (TVP) allow you to send multiple rows of data as a parameter into SQL queries. TVPs are flexible. They can be used in both raw SQL queries and with stored procs, and can be used in all types of queries, from inserts to selects. In this article, I’ll show how to use TVPs … Read more

C# – Remove a set of characters from a string

The fastest and simplest way to remove a set of characters from a string is to use StringBuilder + List<char>, like this: I compared this with three other approaches. I did 100,000 iterations with a string with 2500 characters and a list of 15 characters to remove. This StringBuilder approach is almost 2x faster than … Read more