Tag Archives: lists

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

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 C#, C# programming, equality, equatable, example, example program, IEquatable, LINQ, lists, miscellany, OOP, sequences, unordered sequences, Windows Forms programming | 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 C#, C# programming, equality, equatable, example, example program, IEquatable, lists, miscellany, OOP, sequences, Windows Forms programming | 2 Comments

List Dictionary keys and values in C#

Posted on February 13, 2018 by Rod Stephens

A Dictionary object’s Keys property is a KeyCollection containing the dictionary’s keys. Similarly, its Values property is a ValueCollection containing the dictionary’s values. These collections are slightly different from the List objects that you probably use in your code. In … Continue reading →

Posted in algorithms, controls, lists | Tagged algorithms, C#, C# programming, controls, dictionary, example, example program, KeyCollection, ListBox, lists, ToArray, ValueCollection, Windows Forms programming | Leave a comment

Make an owner-drawn ListBox that justifies columns in C#

Posted on December 24, 2017 by Rod Stephens

This example shows how you can use an owner-drawn ListBox to left and right align values in columns. The following examples show different ways to align values in columns. Draw aligned columns of data in C# Format values in a … Continue reading →

Posted in controls, fonts, graphics, lists, user interface | Tagged align text, C#, C# programming, column, controls, example, example program, fonts, graphics, grid, justify text, left justified, ListBox, lists, owner-drawn ListBox, right justified, row, user interface, Windows Forms programming | Leave a comment

Draw aligned columns of data in C#

Posted on December 22, 2017 by Rod Stephens

This example draws a series of rows with aligned columns either left or right justified. The program uses the following code to define the data it will draw and the row and column alignments. // The values. private string[][] Values … Continue reading →

Posted in fonts, graphics, lists | Tagged align text, aligned columns, C#, C# programming, column, example, example program, fonts, graphics, grid, justify text, left justified, lists, right justified, row, Windows Forms programming | 1 Comment

Iterate over the items in arrays and lists in C#

Posted on July 3, 2017 by Rod Stephens

You can use a foreach loop to iterate over the items in arrays, lists, collections, and other objects that have a GetEnumerator method. These loops are often more convenient than for or while loops because you don’t need to worry … Continue reading →

Posted in arrays, lists, syntax | Tagged arrays, C#, C# programming, collections, enumerate, example, example program, foreach, iterate, lists, loop, syntax, Windows Forms programming | Leave a comment

Display database records without data binding in C#

Posted on May 3, 2017 by Rod Stephens

Many programs use data binding to display database records. That method is easy (at least as far as the code you write is concerned), but it’s not very flexible. This example shows how you can display database records without data … Continue reading →

Posted in controls, database, lists, user interface | Tagged C#, C# programming, controls, data binding, database, database records, example, example program, ExecuteReader, lists, OleDbDataReader, records, user interface, Windows Forms programming | 1 Comment

Initialize lists from databases without binding in C#

Posted on May 2, 2017 by Rod Stephens

Note that this is a very manual way to initialize lists. Often you can display data more easily by using data binding. In this example, I added the Access database file Books.mdb to the project and set its “Copy to … Continue reading →

Posted in controls, database, lists, user interface | Tagged C#, C# programming, controls, database, example, example program, initialize lists, ListBox, lists, OLE DB, OleDbConnection, user interface, Windows Forms programming | 1 Comment

Make a list without duplicates in C#

Posted on March 9, 2016 by RodStephens

This example builds a list of Person objects without duplicates. The following code shows the Person class. public class Person : IEquatable<Person> { public string FirstName, LastName; public Person(string first_name, string last_name) { FirstName = first_name; LastName = last_name; } … Continue reading →