Monthly Archives: April 2018

Make extension methods that pick random items from arrays or lists in C#

Posted on April 30, 2018 by Rod Stephens

This example uses a simple but useful technique to let you pick random items from arrays and lists. The following code defines RandomElement extension methods that pick random items. public static class ArrayExtensions { // The random number generator. private … Continue reading →

Posted in arrays, extension methods, lists | Tagged , , , , , , , , , | 1 Comment

Draw a Pythagoras tree fractal in C#

Posted on April 27, 2018 by RodStephens

A Pythagoras tree (or Pythagorean tree) is a fractal tree built from squares. It starts with a square that forms the tree’s base. The program then makes the Pythagoras tree by recursively attaching two smaller branches to the original branch. … Continue reading →

Posted in drawing, fractals, graphics, recursion | Tagged , , , , , , , , , , | 7 Comments

Perform set operations on enumerable lists in C#

Posted on April 26, 2018 by Rod Stephens

To demonstrate set operations, this example creates two lists of Person objects. The Person class implements IEquatable. The code then uses the following code to display the lists and their intersection, union, difference, and exclusive or (xor). // Display the … Continue reading →

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Draw a Sierpinski pentagon in C#

Posted on April 25, 2018 by RodStephens

In a Sierpinski pentagon, larger pentagons are recursively divided into five smaller pentagons with a sixth uncolored pentagon in the center. The following picture shows the first four levels of the resulting fractal. For this example, I decided to think … Continue reading →

Posted in drawing, fractals, graphics, recursion | Tagged , , , , , , , , , , | 6 Comments

The most popular posts at C# Helper over the last 12 months

Posted on April 24, 2018 by Rod Stephens

Just for fun, here’s a list of the C# Helper web site’s most popular posts over the last 12 months. This isn’t “fair” to the most recent posts because they haven’t been posted for as long. I still think it’s … Continue reading →

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Determine whether two lists contain the same sequences of objects in different orders in C#

Posted on April 24, 2018 by Rod Stephens

The SequenceEqual method determines whether two IEnumerable sequences contain the same objects in the same order. There is a simple way to determine whether the lists contain the same objects in different orders: sort the objects and then call SequenceEqual. … Continue reading →

Posted in LINQ, lists, miscellany, OOP | Tagged , , , , , , , , , , , , , | Leave a comment

Determine whether two lists contain the same sequences of objects in C#

Posted on April 23, 2018 by Rod Stephens

The IEnumerable interface provides a SequenceEqual method that determines whether two IEnumerable sequences contain the same objects. Normally, it uses reference equality so it considers two objects equal only if they refer to the same instance. However, if the objects … Continue reading →

Posted in lists, miscellany, OOP | Tagged , , , , , , , , , , , | 2 Comments

Draw ransom note text in a RichTextBox in C#

Posted on April 23, 2018 by Rod Stephens

This example is similar to the post Draw ransom note text in C# but it writes text into a RichTextBox instead of on a PictureBox. This has the following advantages. The code is simpler The RichTextBox can arrange text more … Continue reading →

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Draw ransom note text in C#

Posted on April 22, 2018 by Rod Stephens

This example draws each of the characters in a string in a different random font to produce a ransom note text effect. The program starts by using the following code to create arrays holding font names and brushes from which … Continue reading →

Posted in graphics, strings | Tagged , , , , , , , , , , , , | 1 Comment

Find duplicate files in C#, Part 4 of 4

Posted on April 19, 2018 by Rod Stephens

The last three posts described an application that searches for duplicate files and removes them. The program seems to work fairly well, at least for small test directories. When I tried it on a directory containing around 8,000 files, however, … Continue reading →

Posted in algorithms, cryptography, files, system, tools | Tagged , , , , , , , , , , , , , , , , , , | 1 Comment