Daily micro-tips for C#, SQL, performance, and scalable backend engineering.
The null conditional operator (?.) is colloquially referred to as the “Elvis operator” because of its resemblance to a pair of dark eyes under a large quiff of hair. The null conditional is a form of a member access operator (the .). Here’s a simplified explanation for the null conditional operator: The expression A?.B evaluates to B if the left operand (A) […]
The null-coalescing operator ?? returns the value of its left-hand operand if it isn’t null; otherwise, it evaluates the right-hand operand and returns its result. The ?? operator doesn’t evaluate its right-hand operand if the left-hand operand evaluates to non-null. int? myValue = null; int result = myValue ?? -1; //result = -1; Syntax: p ?? q Here, p is […]
When you declare a variable in a .NET application, it allocates some chunk of memory in the RAM. This memory has three things: the name of the variable, the data type of the variable, and the value of the variable. That was a simple explanation of what happens in the memory, but depending on the […]
That StackOverflow answer so far is the best one I have ever seen: This is an excellent video on youtube which demonstrates how these interfaces differ, worth a watch. Below goes a long descriptive answer to it. The first important point to remember is IQueryable interface inherits from IEnumerable, so whatever IEnumerable can do, IQueryable can also do. There are many differences […]
Let’s say we haveStartDate and EndDate and those are of type DateTime. If you want to have an int value as a result then: int theResult = (EndDate – StartDate).Days; And if you want to have a double value as a result then: double theResult = (EndDate – StartDate).TotalDays;
C# has a static constructor for this purpose. static class YourClass { static YourClass() { // perform initialization here } } A static constructor is used to initialize any static data, or to perform a particular action that needs to be performed once only. It is called automatically before the first instance is created or […]
By design, GridViewDataComboBoxColumn does not render (Blank) and (NonBlank) items if the HeaderFilterMode property is set to CheckedList. However, you can add these items in the HeaderFilterFillItems event handler. Just call the FilterValue.CreateShowBlanksValue and FilterValue.CreateShowNonBlanksValue methods. <dx:ASPxGridView ID=”grid” runat=”server” AutoGenerateColumns=”False” DataSourceID=”dsCategories” KeyFieldName=”CategoryID” OnHeaderFilterFillItems=”grid_HeaderFilterFillItems”> <Columns> <dx:GridViewDataTextColumn FieldName=”CategoryID”> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn FieldName=”Description”> </dx:GridViewDataTextColumn> <dx:GridViewDataComboBoxColumn FieldName=”CategoryNameNull” Caption=”Category Name”> <Settings HeaderFilterMode=”CheckedList” /> <PropertiesComboBox DataSourceID=”dsCategories” ValueField=”CategoryNameNull” TextField=”CategoryNameNull” /> </dx:GridViewDataComboBoxColumn> </Columns> […]
When working with Code First Migrations, developers often struggle with setting default values at the database level. While you can set a default value in your C# class, doing it directly in the SQL schema is much more robust. Here is how you can achieve this using defaultValue and defaultValueSql. 1. Using Static Default Values […]
We will try to return a string like: “I can text whatever I want with 4 different options in C#. ” with String Interpolation, String Format, String Concat, and String Builder. public class StringOptions { private string data1 = “4”; private string data2 = “C#”; public string StringInterpolation() => ($”I can text whatever I want […]
VS2012: C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class VS2015: C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class VS2017(RC): C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class VS2017(Professional): C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class VS2019 (Enterprise): C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class\Class.cs VS2019 (Professional): C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\Common7\IDE\ItemTemplates\CSharp\Code\1033\Class\Class.cs Starting with Visual Studio 2022 VS is a 64 bit application, meaning the item templates are in C:\Program Files\… instead of C:\Program Files […]
// Gets the value of associated with key “MyKey” from the local resource file (“~/MyPage.aspx.en.resx”) or from the default one (“~/MyPage.aspx.resx”) //The default location for resx files is App_LocalResources object keyValue = HttpContext.GetLocalResourceObject(“~/MyPage.aspx”, “MyKey”);
According to Microsoft: The lock keyword ensures that one thread does not enter a critical section of code while another thread is in the critical section. If another thread tries to enter a locked code, it will wait, block, until the object is released. The lock keyword calls Enter at the start of the block and Exit at the end of the block. lock keyword actually […]
protected void grid_InitNewRow(object sender, DevExpress.Web.Data.ASPxDataInitNewRowEventArgs e) { e.NewValues[“BirthDate”] = new DateTime(1970, 1, 10); e.NewValues[“Title”] = “Sales Representative”; } Here is the result:
Let’s say you send a model called “MyModel” from controller to view. In Controller: … var result = new MyModel() { Id = 1, Name = “Ercan”, FavoriteTeam = “Galatasaray”, FavoriteGame = “Half Life Series” } return View(result); … and now we will send this model which comes with result to Javascript via setName function: […]
Let’s say you have a List of T. And there are Property1, Property2, Property3 in T. If you want to change the value of Property2 in T then you can use: var myList = List<T>; foreach (var item in myList) { item.Property2 = newValue; } or var myList = List<T>; myList.ForEach(x => x.Proprty2 = newValue); […]
DECLARE @MyValue int SELECT @MyValue = Column1 WHERE Column2 > 50 IF @MyValue IS NULL BEGIN RAISEERROR(‘This is my custom message from SQL.’, 16, 1) END ELSE SELECT MyValue END Use an error code within 11-16, or just use 16 for a “general” case. RAISERROR(‘This is my custom message from SQL.’,16,1) Why? Here’s summary of […]
The IndexOf() method returns the index number of the first matched character whereas the LastIndexOf() method returns the index number of the last matched character. using System; public class StringExample { public static void Main(string[] args) { string s1 = “Hello C#”; int first = s1.IndexOf(‘l’); int last = s1.LastIndexOf(‘l’); Console.WriteLine(first); Console.WriteLine(last); } } Output: […]
DateTime myDate; if(DateTime.TryParse(txtBirthDate.Text, out myDate)) { //Valid Date } else { //Invalid Date }
string myList = “9,3,12,43,2”; List<int> intList = myList.Split(‘,’).Select(int.Parse).ToList();
List<int> list = new List<int>() {1,2,3}; string.Join<int>(“,”, list) Join has generic overloads. It is so much easier to use it in that way to convert your list to the different types.
@Html.ListBox( “Countries”, ViewBag.AllCountries as MultiSelectList, new { @class = “form-control”, data_placeholder = “Choose a Country…” } )
string sNumbers = “1,2,3,4,5”; var numbers = sNumbers.Split(‘,’).Select(Int32.Parse).ToList();
new[] {“,”, “/”}.Any(input.Contains) or you can use Regex Regex.IsMatch(input, @”[,/]”);
Table below shows the default value for the different predefined data types. Type Default sbyte, byte, short, ushort, int, uint, long, ulong 0 char ‘\x0000’ float 0.0f double 0.0d decimal 0.0m bool false object null string null As you can see, for the integral value types, the default value is zero. The default value for […]
@Html.TextArea(“Body”, null, new { cols = “55”, rows = “10” }) or
string myValueToSplit = “Istanbul, Tokyo, Seoul, Bangkok, Bali, Minsk, Belgrade, Kiev”; var theFirstValue = myValueToSplit.Split(‘,’)[0]; //OUTPUT: theFirstValue = “Istanbul” //You can change [0] as you wish. //For example, if you want to get Kiev, make it [7]
You can assign an id to the <script> element and passing the arguments as data-* attributes. The resulting <script> tag would look something like this:
You need to define a length when specifying the varchar parameter: SqlParameter TheFirstJob = cmd.Parameters.Add(“@spParam”, SqlDbType.VarChar, 50); Note: You should use the same length as defined in your SQL Server stored procedure.
Let’s say we have a Nullable DateTime named StartTime [DisplayFormat(DataFormatString = “{0:dd.MM.yyyy}”)] public Nullable<System.DateTime> StartTime { get; set; }
To initialize DataRow’s default values handle InitNewRow event of the required ASPxGridView control and initialize the default values by using e.NewValues dictionary in the following manner: