Questions tagged [c#]
C# (pronounced "see sharp") is a high-level, statically typed, multi-paradigm programming language developed by Microsoft. C# code usually targets Microsoft's .NET ecosystem, which include .NET, .NET Framework, .NET MAUI, and Xamarin among others. Use this tag for questions about code written in C# or about C#'s formal specification.
1,619,931
questions
2125
votes
14
answers
1.5m
views
AddTransient, AddScoped and AddSingleton Services Differences
I want to implement dependency injection (DI) in ASP.NET Core. So after adding this code to ConfigureServices method, both ways work.
What is the difference between the services.AddTransient and ...
- 26.9k
2107
votes
114
answers
1.8m
views
How do I remedy "The breakpoint will not currently be hit. No symbols have been loaded for this document." warning?
A C# desktop application (on the Visual Studio Express edition) worked, but then it didn't work 5 seconds later.
I tried the following:
Ensure debug configuration, debug flag, and full debug ...
2015
votes
18
answers
707k
views
What do two question marks together mean in C#?
Ran across this line of code:
FormsAuth = formsAuth ?? new FormsAuthenticationWrapper();
What do the two question marks mean, is it some kind of ternary operator?
It's hard to look up in Google.
- 192k
1908
votes
16
answers
1.5m
views
Type Checking: typeof, GetType, or is?
I've seen many people use the following code:
Type t = typeof(SomeType);
if (t == typeof(int))
// Some code here
But I know you could also do this:
if (obj1.GetType() == typeof(int))
// Some ...
- 30k
1897
votes
20
answers
435k
views
Proper use of the IDisposable interface
I know from reading Microsoft documentation that the "primary" use of the IDisposable interface is to clean up unmanaged resources.
To me, "unmanaged" means things like database ...
- 26.5k
1867
votes
26
answers
2.3m
views
What is a NullReferenceException, and how do I fix it?
I have some code and when it executes, it throws a NullReferenceException, saying:
Object reference not set to an instance of an object.
What does this mean, and what can I do to fix this error?
1866
votes
4
answers
122k
views
Is there a reason for C#'s reuse of the variable in a foreach?
When using lambda expressions or anonymous methods in C#, we have to be wary of the access to modified closure pitfall. For example:
foreach (var s in strings)
{
query = query.Where(i => i.Prop ...
- 155k
1857
votes
10
answers
1.4m
views
Calling the base constructor in C#
If I inherit from a base class and want to pass something from the constructor of the inherited class to the constructor of the base class, how do I do that?
For example, if I inherit from the ...
- 115k
1764
votes
14
answers
672k
views
What does the [Flags] Enum Attribute mean in C#?
From time to time I see an enum like the following:
[Flags]
public enum Options
{
None = 0,
Option1 = 1,
Option2 = 2,
Option3 = 4,
Option4 = 8
}
I don't understand what ...
- 35.2k
1762
votes
8
answers
992k
views
How to loop through all enum values in C#? [duplicate]
This question already has an answer here:
How do I enumerate an enum in C#? 26 answers
public enum Foos
{
A,
B,
C
}
Is there a way to loop through the possible values of Foos?
...
- 22.9k
1727
votes
29
answers
253k
views
Why not inherit from List<T>?
When planning out my programs, I often start with a chain of thought like so:
A football team is just a list of football players. Therefore, I should represent it with:
var football_team = new ...
- 26.2k
1706
votes
30
answers
520k
views
What is the difference between const and readonly in C#?
What is the difference between const and readonly in C#?
When would you use one over the other?
- 351k
1663
votes
16
answers
474k
views
Why is it important to override GetHashCode when Equals method is overridden?
Given the following class
public class Foo
{
public int FooId { get; set; }
public string FooName { get; set; }
public override bool Equals(object obj)
{
Foo fooItem = obj as ...
- 72.9k
1656
votes
42
answers
204k
views
Calculate relative time in C#
Given a specific DateTime value, how do I display relative time, like:
2 hours ago
3 days ago
a month ago
1649
votes
53
answers
1.2m
views
How do you convert a byte array to a hexadecimal string, and vice versa?
How can you convert a byte array to a hexadecimal string and vice versa?