C# Memory Address and Variable

C# memory address and variable

For #2, the & operator will work in the same fashion as in C. If the variable is not on the stack, you may need to use a fixed statement to pin it down while you work so the garbage collector does not move it, though.

For #1, reference types are trickier: you'll need to use a GCHandle, and the reference type has to be blittable, i.e. have a defined memory layout and be bitwise copyable.

In order to access the address as a number, you can cast from pointer type to IntPtr (an integer type defined to be the same size as a pointer), and from there to uint or ulong (depending on the pointer size of the underlying machine).

using System;
using System.Runtime.InteropServices;

[StructLayout(LayoutKind.Sequential)]
class Blittable
{
    int x;
}

class Program
{
    public static unsafe void Main()
    {
        int i;
        object o = new Blittable();
        int* ptr = &i;
        IntPtr addr = (IntPtr)ptr;

        Console.WriteLine(addr.ToString("x"));

        GCHandle h = GCHandle.Alloc(o, GCHandleType.Pinned);
        addr = h.AddrOfPinnedObject();
        Console.WriteLine(addr.ToString("x"));

        h.Free();
    }
}

Can i get physical address of a variable or object in C#?

Yes, with unsafe code (at least the virtual address, not the raw physical memory address, but that's just what you want).

Have a look at MSDN: How to: Obtain the Address of a Variable (C# Programming Guide) for details. It guides you through compiling the following example (it requires unsafe code to be enabled in the project properties or the /unsafe switch) and what traps you could experience when getting the location of moveable variables, which require the fixed keyword to stay at the same location, basically said.

int number;
int* p = &number; //address-of operator &

Change the memory address of an object in C#

Only to mark this question as answered to be useful, I pasted my comment here again.

It won't be easy to do so.
Because in .Net, GC must track the address of all of the variables to de-allocate the pointer, after releasing the last anchor of the variable.
Also, it's illegal because each application has it's own Application Domain and by default, no application is allowed to access to out of its boundary.

Please consider marking the question as answered.
Thanks a lot.

c# change variable memory address

Did you know you can use pointers in C#?

int someVariable = 0;

unsafe
{
    int* addr = &someVariable;
    *addr = 42;
}

Console.WriteLine(someVariable); // Will print 42

If you already have an address you can just write:

int* addr = (int*)0xDEADBEEF;

Or, from an IntPtr:

var intPtr = new IntPtr(0xDEADBEEF);
int* addr = (int*)intPtr.ToPointer();

Getting the address location of variable

You will have to pin the object before extracting its address. Otherwise, the GC is free to move it around.

object variable = new object();
GCHandle handle = GCHandle.Alloc(variable, GCHandleType.Pinned);
IntPtr address = handle.AddrOfPinnedObject();

Normally you would only do this in scenarios requiring some type of unmanaged interop. However, even then there is rarely a need for this type of manual manipulation.

How does memory work in c# with variable assignment?

Its not pointer, Its reference in C#.

Yes, They will point to the same memory address. I am giving you one simple example below.

using System;
            
public class Program
{
    public class ABC {
    public int x;
    }
    public static void Main()
    {
        ABC a = new ABC();
        a.x = 1;
        ABC b = a;
        b.x = 2;
        ABC c = b;
        c.x = 3;
        Console.WriteLine(a.x);
        Console.WriteLine(b.x);
        Console.WriteLine(b.x);
    }
}

It will print.

3

3

3

Memory address of a variable

Yes, it is possible to obtain a raw pointer to storage in C#. Rather than try to explain it all here, I recommend that you read all of chapter 18 of the C# specification, which discusses this topic in detail.

However, if what you want to do is learn how various different floating point types store values, there are easier ways than looking at them in a debugger. These are all well-documented formats; you can just look them up in wikipedia or msdn and read about how they are laid out in memory.

The binary representation of a Decimal value consists of a 1-bit sign, a 96-bit integer number, and a scaling factor used to divide the 96-bit integer and specify what portion of it is a decimal fraction. The scaling factor is implicitly the number 10, raised to an exponent ranging from 0 to 28.

See http://msdn.microsoft.com/en-us/library/system.decimal.aspx for details.

The binary representation of a double is one sign bit, 11 exponent bits representing an exponent from -1022 to +1023, and 52 bits of mantissa, which are interpreted "1." followed by the 52 bits.

See http://en.wikipedia.org/wiki/Double_precision or my series of articles on floating point issues: http://blogs.msdn.com/ericlippert/archive/tags/Floating+Point+Arithmetic/default.aspx

A float is the same as a double, just half the size: one sign bit, 8 exponent bits, 23 mantissa bits. See http://en.wikipedia.org/wiki/Single_precision_floating-point_format for details.

Store variable at certain memory address C#

Instead of hard-coding a specific memory address, you can use Memory Mapped Files to share a portion of memory between processes.

There's more information on MSDN here:

https://msdn.microsoft.com/en-us/library/dd997372.aspx

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