CODEWITHSUNDEEP
c#
Viku
Viku

Reputation: 2973

how to use class object being created in stack

I am new to c# . So cant figure out the below mentioned concept .

using System;
namespace vivek
{
    class viku
    {
        public void func1()
        {
            Console.WriteLine("Base");
        }
    }
    class Behera
    {
        static void Main(String[] args)
        {
            viku v;
            v.func1();
        }
    }
}

After compiling its showing the below error

 error CS0165: Use of unassigned local variable 'v'

Upvotes: 1

Views: 216

Answers (5)

Scott Chamberlain
Scott Chamberlain

Reputation: 127583

You seem to be a C++ guy, one thing to help you visualize (but it's not exactly true, its just an analogy) is think of classes in C# as always being pointer refrences in C++.

So if we re-wrote your original code to the "equivilant" in C++ (ignore the memory leak, like I said it is just a basic analogy, not a exact truth) it would be:

namespace vivek
{
    class viku
    {
        public:
        void func1()
        {
            Console::WriteLine("Base");
        }
    }

    class Behera
    {
        static void Main(String[] args)
        {
            viku* v;
            v->func1();
        }
    }
}

Now (if I assumed correctly that you know C++) it is obvious why your call to v did not work, it does not point at any instance of the viku class.

Upvotes: 2

Damien_The_Unbeliever
Damien_The_Unbeliever

Reputation: 239724

There's no way for you to instruct the compiler to create an object on the stack in C# - you're working in a managed memory environment now, where the managed side of things has rules that decide where objects are created.

What ends up on the stack is purely an implementation detail. Usually, it will be your reference variables and any local value types1, provided that these variables and value types are not being hoisted due to lambdas, and that you're not writing code in an iterator or async method2.

To create any reference type object (class declares a reference type, struct or enum declares a value type), you have to use new.

1The fact that local value types sometimes end up on the stack is, as I say, an implementation detail. But there's a persistent myth that "value types go on the stack, reference types go in the heap". You shouldn't change your class to a struct just to force it to go on the stack (which it won't always be anyway).

2In all of these situations, the compiler actually re-writes the code that you've written, and what look like local variables become, in fact, fields of a new class that the compiler constructs for holding them.

Upvotes: 5

Sergey Gavruk
Sergey Gavruk

Reputation: 3568

To create an object, you need to call a contructor

viku v = new viku();

or even shorter

var v = new viku();

You should read this article about constructors

Upvotes: 1

Mukesh Kumar Singh
Mukesh Kumar Singh

Reputation: 653

I dont have idea about c# syntax but.. i think it might be

viku v=new viku(); v.func1();

Upvotes: 0

Adil
Adil

Reputation: 148150

You need to instanstiate object of class.

Change

viku v;

To

viku v = new viku();

Upvotes: 2

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