Category Archives: extension methods

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 arrays, C#, C# programming, example, example program, extension methods, lists, random, random items, Windows Forms programming | 1 Comment

Initialize a TreeView control to display a directory hierarchy in C#

Posted on November 21, 2017 by Rod Stephens

This example adds the following LoadFromDirectory extension method to the TreeView control. // Initialize the TreeView from a directory, // its subdirectories, and their files. public static void LoadFromDirectory(this TreeView trv, string directory, int folder_img, int file_img) { DirectoryInfo dir_info … Continue reading →

Posted in controls, directories, extension methods, files, user interface | Tagged C#, C# programming, controls, directories, directory hierarchy, example, example program, extension methods, files, TreeNode, TreeView, TreeView control, user interface, Windows Forms programming | Leave a comment

Make subarray extension methods in C#

Posted on October 23, 2017 by Rod Stephens

The Array class’s Copy method can copy a subarray from one array to another, but it requires that you figure out how many items you want to copy. It will also copy parts of a two-dimensional array, but it only … Continue reading →

Posted in arrays, extension methods | Tagged array, arrays, C#, C# programming, copy array entries, example, example program, extension methods, subarray, Windows Forms programming | Leave a comment

Make extension methods to generate random double values in C#

Posted on July 5, 2017 by Rod Stephens

This example adds extension methods to the Random class to generate double values within a specified range. The Random class provides methods for generating pseudo-random numbers. The Next method has three overloaded versions that produce a non-negative integer, an integer … Continue reading →

Posted in extension methods, mathematics | Tagged C#, C# programming, example, example program, extension methods, mathematics, NextDouble, random, random class, random numbers, Windows Forms programming | 1 Comment

Print a ListView control’s contents on multiple pages in C#

Posted on June 30, 2017 by Rod Stephens

This example continues the following two examples: Print a ListView with large contents in C# Print the contents of a ListView control in C# Read those examples for an overview of the basic procedure. This example prints the contents of … Continue reading →

Posted in controls, extension methods, printing | Tagged C#, C# programming, controls, example, example program, extension methods, ListView, multi-line data, multiline data, print ListView, print ListView contents, print ListView data, printing, Windows Forms programming | 4 Comments

Make rectangle extension methods in C#

Posted on June 21, 2017 by Rod Stephens

This example shows how to add rectangle extension methods to the Rectangle and RectangleF structs. The Rectangle and RectangleF structs have several useful properties for determining their geometry such as Left, Right, Top, and Bottom, but they have no midpoint … Continue reading →

Posted in drawing, extension methods, graphics | Tagged C#, C# programming, center, drawing, example, example program, extension methods, graphics, midpoint, MidX, MidY, Rectangle, rectangle extension methods, RectangleF, Windows Forms programming | Leave a comment

Use string extension methods to validate Social Security numbers in C#

Posted on June 19, 2017 by Rod Stephens

This example defines three extension methods that return true if strings contain Social Security numbers. Recall that you must add extension methods to a static class and that the methods must be static. This example begins by defining a Matches … Continue reading →

Posted in extension methods, extensions, regular expressions, strings | Tagged C#, C# programming, example, example program, extension methods, extensions, regular expressions, Social Security numbers, strings, Windows Forms programming | 2 Comments

Use an improved extension method to calculate standard deviation in C#

Posted on March 8, 2017 by RodStephens

The example Calculate standard deviation in C# makes an extension method that calculates standard deviation for an IEnumerable of integers. Unfortunately because that example works with integers, it cannot work with other data types. Rian Meier showed me this method, … Continue reading →

Posted in algorithms, extension methods, mathematics | Tagged algorithms, C#, C# programming, example, example program, extension methods, mathematics, standard deviation, stddev, variance, Windows Forms programming | Leave a comment

Remove non-printable ASCII characters from a string in C#

Posted on January 17, 2017 by Rod Stephens

The following TrimNonAscii extension method removes the non-printable ASCII characters from a string. public static string TrimNonAscii(this string value) { string pattern = “[^ -~]+”; Regex reg_exp = new Regex(pattern); return reg_exp.Replace(value, “”); } In ASCII, the printable characters lie … Continue reading →

Posted in extension methods, strings | Tagged ASCII, C#, C# programming, example, example program, extension methods, non-printable ASCII characters, non-printable characters, non-printing characters, remove non-printable characters, remove non-printing characters, strings, Windows Forms programming | 7 Comments

Sort ListView controls by all columns or clicked columns in C#

Posted on December 11, 2016 by Rod Stephens

The ListView control provides features to sort its values but by default it doesn’t use them. This example shows how you can add extension methods to the control to make it sort on all columns or on clicked columns. This … Continue reading →