Develop Reference

Can I have two entry points in C#

Would it be possible to use two entry points in C# instead of just having the one. For example when I have this:
using System;
namespace learning
{
class cool
{
static void Main(string[] args)
{
}
}
}
Would it be possible to have another entry point such as secondary that the program executes once the main entry point has finished.

You may want to do something like this:
class Program {
public static void EntryPoint1(string[] args) {
// Code
}
public static void EntryPoint2(string[] args) {
// Code
}
public static void Main(string[] args) {
EntryPoint1(args);
EntryPoint2(args);
}
}
Just make sure to not modify args during EnteryPoint1 or if you want to, clone them like this:
class Program {
public static void EntryPoint1(string[] args) {
// Code
}
public static void EntryPoint2(string[] args) {
// Code
}
public static void Main(string[] args) {
EntryPoint1(args.Clone());
EntryPoint2(args.Clone());
}
}

In C#, you specify the entry point using the /main: compiler option.
Imagine that the code containing containing two main() methods as follow :
namespace Application {
class ClassA {
static void main () {
// Code here
}
}
class ClassB {
static void main () {
// Code here
}
}
To use ClassA.main() as your entry point, you would specify the following when compiling:
csc /main:Application.ClassA hello.cs

You can only have a single entry point, but you can write two separate methods, call the first one, and then the second one. You will achieve what you're describing.
using System;
namespace learning
{
class cool
{
static void Main(string[] args)
{
PartOne();
PartTwo();
}
void PartOne() {
// Something happens here
}
void PartTwo() {
// Something else happens here
}
}
}
Additionally (depending on how the program starts up) you can send in arguments to specify which method you want to execute (if you don't need both of them to execute). Then you can just do an "if/else" statement that will decide which method to run depending on the arguments passed into Main

Why use static methods in program.cs C#? [duplicate]

This question already has answers here:
When to use static methods
(24 answers)
Closed 2 years ago.
I always knew that I have to use static methods but I wonder why?
As you can see below I have to make "MigrateDatabase" Static
using System;
namespace OdeToFood
{
public class Program
{
public static void Main(string[] args)
{
MigrateDatabase();
}
private static void MigrateDatabase()
{
//.....
}
}
}

Let's just be clear, the only reason MigrateDatabase has to be static in this case is because you're calling it from a static method (Main). If instead MigrateDatabase was an instance method on a class, you could instantiate that class and call it
using System;
namespace OdeToFood
{
public class Program
{
public static void Main(string[] args)
{
var migration = new Migration();
migration.MigrateDatabase();
}
}
public class Migration
{
private void MigrateDatabase()
{
//.....
}
}
}
You could also put it as a instance method on Program if you're instantiating an instance of that class
using System;
namespace OdeToFood
{
public class Program
{
public static void Main(string[] args)
{
var program = new Program();
program.MigrateDatabase();
}
private void MigrateDatabase()
{
//.....
}
}
}

How do I start an Activity from a non-Activity class?

How can I start an Activity from a non-Activity in Xamarin.Forms?
In the main startup project, MyApp.Droid, I have MyActivity.cs.
In the PCL project, MyApp.Plugin.Android, I have a non-activity class, MyClass.cs.
In MyClass.cs I need to run some code in MyActivity.cs.
How can I do that?
Thanks.
MyActivity.cs:
public void MyMethod()
{
// [Working Code...]
}
MyClass.cs:
public void OnSuccess
{
// What should I put here to call MyMethod?
}

something like this should do the trick! (I think, it been a while...)
MyClass.cs:
using System;
namespace MyClass {
public static class Program {
public static void MyMethod()
{
// [Working Code...]
}
}
}
MyActivity.cs:
using System;
using MyClass; //get your other file by the namespace
namespace MyActivity {
public static class Program {
public static void OnSuccess()
{
Program.MyMethod(); //[class name]..MyMethod();
}
}
}

Dynamic parameters in postsharp

I am trying to assign the property dynamically using post sharp. Such as in the below example I would like to have custom logging messages. But the problem is how could I set xname in the attribute part.In the first log I would like to have the logging message would have the persons name in the beginning but the second logging message would have the persons name at the end.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplicationLogging
{
internal static class Program
{
private static void Main()
{
Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
SayHelloInTurkish("Ayse");
SayGoodByeSayHelloInEnglish("Elizabeth");
}
[Trace("xname Loglanıyor Gunaydın")]
private static void SayHelloInTurkish(string personName)
{
Console.WriteLine("Hello, world.");
}
[Trace("Good Bye Logging for xname")]
private static void SayGoodByeSayHelloInEnglish(string personName)
{
Console.WriteLine("Good bye, world.");
}
}
}
using System;
using System.Diagnostics;
using PostSharp.Aspects;
namespace ConsoleApplicationLogging
{
[Serializable]
public sealed class TraceAttribute : OnMethodBoundaryAspect
{
private readonly string category;
public TraceAttribute(string category)
{
this.category = category;
}
public string Category { get { return category; } }
public override void OnEntry(MethodExecutionArgs args)
{
if (args.Method.DeclaringType != null)
Trace.WriteLine(string.Format("Entering {0}.{1}.",
args.Method.DeclaringType.Name, args.Method.Name), this.category);
}
public override void OnExit(MethodExecutionArgs args)
{
if (args.Method.DeclaringType != null)
Trace.WriteLine(string.Format("Leaving {0}.{1}.",
args.Method.DeclaringType.Name, args.Method.Name), this.category);
}
}
}

If I understand correctly, you need something like this (no sanity checking included):
this.category.Replace("xname", (string)args.Arguments[0])
If I did not understand correctly, feel free to comment below.

Clean code which version is correct?

When the only code in there is for a class how would you code it adding public to the default class like so
namespace HW2_2_Spaceship
{
public class Spaceship //added public to the default class
{
static void Main(string[] args)
{
}
or
namespace HW2_1_Book
{
class Book
{
static void Main(string[] args)
{
}
public class Book // added a new class with in the default class
{

In general, each class should have their own file.
Main should be in Program.cs
There are usecases where you can use Inner classes, see Using Inner classes in C#.

//Program.cs, if u use visual studio then ensure you add
// the public access modifier yourself
namespace HW2_2_Spaceship
{
public class Program
{
public static void Main(string[] args)
{
//Do something here
}
}
}
//Book.cs, add the public modifier to the class
namespace HW2_2_Spaceship
{
public class Book
{
//add method and properties here
}
}