class Program
{
static void Main(string[] args)
{
//I want to call the bird method here
}
public void bird(Program program)
{
birdSpeech();
}
public void birdSpeech()
{
Console.WriteLine("Chirp Chirp");
}
}
How do I call bird in the main, I also tried to call the method from a object of the class but that didn't work
Does it even make sense to do this (I try to avoid static methods as much as possible).
If a method can be made static without changing the code, you should make it static. To answer your question though, you can create an instance of Program in your Main function and call the non-static methods through it.
class Program
{
static void Main(string[] args)
{
var p = new Program();
p.bird();
}
public void bird()
{
birdSpeech();
}
public void birdSpeech()
{
Console.WriteLine("Chirp Chirp");
}
}
Could do something like this
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
var p = new Program();
p.bird(p);
}
public void bird(Program program)
{
birdSpeech();
}
public void birdSpeech()
{
Console.WriteLine("Chirp Chirp");
}
}
Related
I'm trying to run a method created in a different class using the "public" access modifier. It seems not to be working like fields. Here's a simple example, could you lead me to a solution?
Thank you.
class Program
{
void Main(string[] args)
{
Hello();
}
}
class Example
{
public void Hello() //Error?
{
Console.WriteLine("Hello world");
}
}
You need to create an instance of the 'Example' class in able to call it's 'Hello' method:
class Program
{
void Main(string[] args)
{
var example = new Example();
example.Hello();
}
}
class Example
{
public void Hello() //Error?
{
Console.WriteLine("Hello world");
}
}
Or: make the Hello method static:
class Program
{
void Main(string[] args)
{
Example.Hello();
}
}
class Example
{
public static void Hello()
{
Console.WriteLine("Hello world");
}
}
just as an example: you need to instantiate an object of the class first to be able to access its members (unless they are static):
class Program
{
void Main(string[] args)
{
Example ex = new Example();
ex.Hello();
}
}
class Example
{
public void Hello()
{
Console.WriteLine("Hello world");
}
}
In C# , in Visual Studio, using a Console Application, is there a way to make methods in a class and call them in main program using readline?
Aka, a way to choose which methods to open when the program is running.
Easiest way is a switch statement for <4 cases, and a Dictionary for 4 or more cases.
class Program
{
private static IDictionary<string, Action> MethodMappings = new Dictionary<string, Action> {
{"Method1", Method1},
{"Method2", Method2},
...
}
public static void Main(string[] args) {
var methodCall = Console.ReadLine();
if (!MethodMappings.ContainsKey(methodCall)) {
//unrecognized command
}
MethodMappings[methodCall].Invoke();
}
private static void Method1() { ... }
private static void Method2() { ... }
}
This is very much possible using Reflection. Here is sample code to help you out:
class Program
{
public static void Hello1()
{
Console.WriteLine("\nHello 1");
}
public static void Hello2()
{
Console.WriteLine("\nHello 2");
}
static void Main(string[] args)
{
while (true)
{
String method = Console.ReadLine();
Type methodType = typeof(Program);
MethodInfo voidMethodInfo = methodType.GetMethod(method);
voidMethodInfo.Invoke(method,null);
}
}
}
For more information you can visit here.
Asking the same question as
Using delegates with non static methods [no picked answer]
so as to bring a closure to it.
So I use #Adam Marshall's solution, it works, but as soon as I start using it, i.e., Testit():
using System;
public class TestClass
{
private delegate void TestDelegate();
TestDelegate testDelegate;
public TestClass()
{
testDelegate = new TestDelegate(MyMethod);
}
public static void Testit()
{
testDelegate();
}
private virtual void MyMethod()
{
Console.WriteLine("Foobar");
}
}
public class Program
{
public static void Main()
{
Console.WriteLine("Hello World");
TestClass.Testit();
}
}
It started to give the followig Error:
A object reference is required for the non-static field, method, or property
You can test it out here .
How to fix it? (Please fix it if possible instead of directing me to other posts, I've read them but am not able to understand them) Thx.
Either everything has to be static or everything has to be instance. You're getting in trouble because you are mixing and matching.
Everything static:
using System;
public class TestClass
{
private delegate void TestDelegate();
static TestDelegate testDelegate; //<-- static
static TestClass() //<-- static
{
testDelegate = new TestDelegate(MyMethod);
}
public static void Testit()
{
testDelegate();
}
private static void MyMethod()
{
Console.WriteLine("Foobar");
}
}
public class Program
{
public static void Main()
{
Console.WriteLine("Hello World");
TestClass.Testit();
}
}
Everything instanced:
using System;
public class TestClass
{
private delegate void TestDelegate();
TestDelegate testDelegate;
public TestClass()
{
testDelegate = new TestDelegate(MyMethod);
}
public void Testit()
{
testDelegate();
}
private void MyMethod()
{
Console.WriteLine("Foobar");
}
}
public class Program
{
public static void Main()
{
Console.WriteLine("Hello World");
var t = new TestClass();
t.Testit(); //<-- non-static
}
}
Output (same in both examples):
Hello World
Foobar
You could use action C# internal delegate. This way you do not have specify the delegate. Then in your static method you could new up your object.
using System;
public class TestClass
{
Action testDelegate;
public TestClass()
{
testDelegate = new Action(MyMethod);
}
public static void Testit()
{
TestClass ts = new TestClass();
ts.testDelegate();
}
private void MyMethod()
{
Console.WriteLine("Foobar");
}
}
public class Program
{
public static void Main()
{
Console.WriteLine("Hello World");
TestClass.Testit();
}
}
Output:
Hello World
Foobar
Hello I am new to programming.
Basically I need to store a method A from class A in variable A from class B inside a method from class B but I cannot seem to find a way.
To give an example:
Class A
public void methodA()
{
*method*
}
Class B
Delegate variableA; //I believe using Delegate is wrong
public void methodB();
{
variableA = ClassA.methodA();
}
Then in Class B there would be another method that will utilize the variable with the stored method.
public void methodC();
{
variableA;
}
This isn't the exact code I have but this is basically the gist of it. Any help is appreciated :)
Edit: Thanks for the help everyone!
ClassA definition:
public class ClassA
{
public void MethodA()
{
Console.WriteLine("Hello World!");
}
}
ClassB definition:
public class ClassB
{
private Action VariableA { get; set; }
public void MethodB(ClassA classA)
{
VariableA = classA.MethodA;
}
public void MethodC()
{
VariableA();
}
}
Program definition:
static void Main(string[] args)
{
ClassA classA = new ClassA();
ClassB classB = new ClassB();
classB.MethodB(classA);
classB.MethodC();
Console.ReadLine();
}
Here is an example:
public class Test
{
private Action<int> hiddenMethod = new Action<int>((i) =>
{
Console.WriteLine(i);
});
public void PublicMethod(int i)
{
hiddenMethod(i);
}
}
And using it:
class Program
{
static void Main(string[] args)
{
Test t = new Test();
t.PublicMethod(21);
Console.Read();
}
}
Use reflection:
public class A
{
public void MethodA()
{
Console.WriteLine("MethodA");
}
public static void StaticMethodA()
{
Console.WriteLine("StaticMethodA");
}
}
public class B
{
MethodInfo mv = typeof(A).GetMethod("MethodA");
MethodInfo smv = typeof(A).GetMethod("StaticMethodA");
public void CheckA(bool useStatic)
{
if (useStatic) smv.Invoke(null, null);
else mv.Invoke(new A(), null);
}
}
class MainClass
{
[STAThread]
public static void Main(string[] args)
{
var b = new B();
b.CheckA(true);
b.CheckA(false);
}
}
See details in MSDN.
Assume I have a code:
class Module1 {
public static void Main(string[] args) {
Module1.level1();
}
public static void level1() {
Module1.level2();
}
public static void level2() {
Module2.level1();
}
}
[DetectWhenFlowExitsClass] // <-- note aspect
class Module2 {
public static void level1() {
Module2.level2();
}
public static void level2() {
Module2.level3();
}
public static void level3() {
throw new SystemException("oops");
}
}
After calling Main() I get a stacktrace:
Unhandled Exception: System.SystemException: oops
at Test.Module2.level3()
at Test.Module2.level2()
at Test.Module2.level1()
at Test.Module1.level2()
at Test.Module1.level1()
at Test.Module1.Main(String[] args)
Question
How to write aspect which detects moment when "control flow" exits code of class Module2?
That is, when Test.Module2.level1() finishes its work [here, due to exception].
Exist any shortcuts for this in PostSharp?
The most basic way would be to use OnMethodBoundaryAspect, which allows you to handle the method entry and method exit advices. You will need to count number of method of each particular class on the stack and when this count goes from 1 to 0, the control is leaving methods of the aspected class.
Here is the sample aspect code:
[Serializable]
public class DetectWhenFlowExitsClass : OnMethodBoundaryAspect
{
[ThreadStatic] private static Dictionary<Type, int> stackCounters;
private Type declaringType;
public override bool CompileTimeValidate(MethodBase method)
{
declaringType = method.DeclaringType;
return true;
}
private void EnsureStackCounters()
{
if (stackCounters == null)
stackCounters = new Dictionary<Type, int>();
}
public override void OnEntry(MethodExecutionArgs args)
{
EnsureStackCounters();
int counter;
stackCounters.TryGetValue(declaringType, out counter);
stackCounters[declaringType] = ++counter;
}
public override void OnExit(MethodExecutionArgs args)
{
EnsureStackCounters();
int counter;
stackCounters.TryGetValue(declaringType, out counter);
stackCounters[declaringType] = --counter;
if (counter == 0)
Console.WriteLine("Control leaving class {0}", declaringType.Name);
}
}
You will probably need to tinker with this aspect implementation a bit, but it works in basic situations.