C#: When to use void while creating a method?

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Hey guys,

I'm trying to implement a sample code here, I just want to ask:

1. Whenever I create a class, by default if the class name is Car1, it automatically has "public class Car1" and inside it, the first method "public Car1". How come, that whenever I create another method let's say: Car2 inside "public class Car1". But out side the curly bracket of "public Car1" it says "Method must have a return type"?

C#

public class Car1{
public Car1()

{
//Stuff here
}

public car2()    <<<===============This will cause an error method must have a return type, unless I put  void before the car2
{
//Stuff here
}

}

There you go, I hope someone can tell me because I'm trying to create a new method that will send a data to another class in another file and I'm not sure if I will be able to do that with the use of void.

Thanks,

Posted 28-Jan-14 19:20pm

KatsuneShinsengumi

Updated 16-Apr-14 4:09am

Rahul VB

v2

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Rahul VB 29-Jan-14 2:42am

Question up voted, so that anyone who sees it, will learn the very basics of Class, Constructor.

4 solutions

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Sandeep Singh Shekhawat · Accepted Answer · 2014-01-28T19:28:00

Here You need to know fewthings. These are

1. Constructor : It's name same as class name and it doesn't have any return type.
2. Method : Each method has a return type. If you don't return any value from a method then it is void type.
3. void : Void is a return type and it used when method doesn't returns.

In your example Car1 is your class so it constructor is

public car1()
{
}

But Car2() is not a constructor for Car1. It is a method for Car1 so it should be a valid return type.

Check following example:

C#

using System;

namespace PrimeNumber
{
    class Program
    {
        static void Main(string[] args)
        {
            Car2 car = new Car2(100.12f);
            Console.WriteLine("Speed is :{0}",car.Speed);
            Console.Read();
        }
    }

    public class Car1
    {
        private float mSpeed;

        public Car1(float speed)
        {
            mSpeed = speed;
        }
        public float Speed
        {
            get { return mSpeed; }
        }
    }
    public class Car2 : Car1
    {
        public Car2(float speed)
            : base(speed)
        {
        }

    }

}

Karthik_Mahalingam · Accepted Answer · 2014-01-28T19:32:00

Solution 2

Pls go through these topics

Constructors[^]
c# Constructors[^]
An Intro to Constructors in C#[^]

Posted 28-Jan-14 19:32pm

Karthik_Mahalingam

Comments

KatsuneShinsengumi 29-Jan-14 2:46am

Hi, I have a question, how this code work?

public mySampleClass(): this(10)
This is from the link you gave me. I dot get the "this(10)" part, I'm sorry, Im just new to this stuff and really want to be in web dev. I'm following a book and got stuck to the constructors part.

Thanks,

Karthik_Mahalingam 29-Jan-14 3:18am

this will work if it has a constructor of integer parameter.
as

public class mySampleClass
{
public mySampleClass()
: this(10)
{
}
public mySampleClass(int a)
{
}
}

KatsuneShinsengumi 29-Jan-14 3:26am

So this means that the mySampleClass constructor has an int named "a" and has a value of 10?

Karthik_Mahalingam 29-Jan-14 3:57am

a is the name of the parameter, it can be of any name, event katsune :) also... it will work...

Praveen_P · Accepted Answer · 2014-01-28T19:42:00

Solution 3

Constructors are the special types of methods of a class which get executed when it's object is created. Constructors are responsible for object initialization and memory allocation of its class.They have same name as of class and have no return type.

Different Constructor types are as :
Default Constructor
Parameterized constructor
Private Constructor
Static Constructor
Copy Constructor

Here Car1() is the constructor so it has no return type , also Car1() doesn't take any argument therefore it is an example of default/non-parameterized constructor .

Car2() is a method so it must have a return type

Posted 28-Jan-14 19:42pm

Praveen_P

Updated 28-Jan-14 19:47pm

v2

Comments

Rahul VB 29-Jan-14 2:44am

Very nice, please tell me what is a "Copy constructor"?

Praveen_P 29-Jan-14 3:22am

Copy constructor creates an object by coping value from another object.

Rahul VB 29-Jan-14 3:53am

thanks a ton

Rahul VB 29-Jan-14 4:30am

Thanks, brother i have referred your solution and improved mine. Please go through and tell me if it is correct. Thanks.

Praveen_P 29-Jan-14 6:28am

thank you , plz refer these url's http://www.aspdotnet-suresh.com/2013/09/csharp-constructor-example-types-of-constructor-in-csharp.html , http://www.c-sharpcorner.com/UploadFile/0c1bb2/constructors-and-its-types-in-C-Sharp/ where u can find sample code for different constructor types

Rahul VB · Accepted Answer · 2014-01-28T20:30:00

Hello,

what i can see is that you are confused between a constructor and a class. Lets start with some basics:

Quote:
What is a Class?

Class is a collection of related things(it should be). Classes are used to organize the functionality of your code.

For example you have a class which contains all the methods related to networking: For example, pinging, creating a socket etc.

When i create a class i am just creating its blueprint. How should i realize it? to do that i will say:

Class1 c = new Class1();

Please note: the

Quote:
new

keyword is used to allocate memory for the

Quote:
object

of the class.

Pay attention to the words i have put in quotes. I can use the functionality of that class using its object. So to use the functionality of Class1, i can now use c.

So i say c.some_method();

Quote:
What is a constructor?

Constructor can be called a special method which is used to initialize the fields of a class.Its name is the same as that of the class. Constructors are of 2 types: Parametrized and Parameter less.

As explained by my friend(Praveenpk3) in Solution 3 there are many other types of constructors, referring to his solution,

Quote:
Different Constructor types are as :
Default Constructor
Parameterized constructor
Private Constructor
Static Constructor
Copy Constructor

Look at the code below:

C#

public class Class2
   {
     string s;

     public Class2()   ////parameterless constructor
      {

      }

      public Class2(string s) ////parametrized constructor , because it accepts a string.
      {
          this.s = s;
          Console.WriteLine(this.s);

      }

      ////Please note there is no return type for a constructor.
      ///Homework1: Why is there no return type for a constructor?
      ///Homework2 : Whats the difference between "this.s" and "s"?


   }

Quote:
Why to use a constructor?

- Suppose that you want to initialize some field of a class at start up? how do you do that?
using the code i showed you.Experience will help you figure out when to use a parameterized constructor.

Quote:
What is a method?

A method is some thing which performs some operation or function.
It can take one/many inputs perform an action

Quote:
depending on those inputs

and return results.
For example :

C#

public bool method1(int i)
       {

           return i == 1; ///returns true of i =1

       }

I dont have a void here. Why? because it does not return a void(which means nothing/empty). It returns something, a result, whose type is a bool.

It may not take any inputs and simply return the results.

C#

public bool method1()
      {

          return false;

      }

It may neither take any input nor return any results.

C#

public void method2()
      {

          Console.WriteLine("hello");

      }

I hope this has helped you to learn the significance of a return type.

Quote:
Homework3:
public bool method1(int i)
{

return i == 1; ///returns true of i =1

}

public bool method1()
{

return false;

}

What is the above phenomena called? Why to use it?

Start studying and happy learning.

One last thing: Please do the homework, will be good for you.

Thanks

C#: When to use void while creating a method?

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