How can I convert this code(VB) to C# ?

Hi,

This is manually translated but still untested (and I don't know what you're trying to do with this..

Anyway, here is the partially-refactored code:

public void Method()
{
    Random rnd = new Random();
    for (int i = 1; i <= 6; i++)
    {
        // RandomButton is a collection, right?
        RandomButton[i].Image = null;
    }
    for (int i = 1; i <= 6; i++)
    {
        bool checkSuccessful = true;
        int randomNumber = 6 * rnd.Next() + 1;
        // Kiểm tra trùng này !
        for (int j = 1; j < i - 1; j++)
        {
            // Also List1 is a collection?
            if (randomNumber == List1[j])
            {
                // Never use "GOTO"! use a variable to check.
                checkSuccessful = false;
                // Not nice but this is the only short solution I found for.
                break;
            }
        }
        // Check if the inner-loop-check was not failing.
        if (checkSuccessful)
        {
            List1[i] = randomNumber;
        }
    }
}

Hope this helps.

Best regards and happy coding,
Stops

Here is your C# code:

int i = 0;
int j = 0;
int Rand = 0;
ClicksMouse = 0;
for (i = 1; i <= 6; i++) {
    Radombutton(i).Image = null;
}

for (i = 1; i <= 6; i++) {
    A1:
    VBMath.Randomize();
    Rand = Conversion.Int(6 * VBMath.Rnd() + 1);

    //Kiểm tra trùng này !
    for (j = 1; j <= i - 1; j++) {
        if (Rand == List1(j))
            goto A1;
    }
    List1(i) = Rand;
}

Speaking about the tricky part (random extraction of numbers without repetitions) you don't need to 'convert' exactly that ugly VB, you may write a better code doing the same thing, try, for instance:

static void Main()
    {
        const int SIZE = 6;
        int[] list = new int[SIZE];
        Random rnd = new Random();
        for (int i = 0; i < SIZE; i++)
        {
            list[i] = i+1;
        }
        for (int i = 0; i < SIZE - 1; i++)
        {
            int r = rnd.Next(SIZE-i);

            int tmp = list[SIZE - 1];
            list[SIZE - 1] = list[r];
            list[r] = tmp;
        }
        for (int i = 0; i < SIZE; i++ )
            Console.WriteLine("list[{0}]={1}", i, list[i]);
    }

The algorithm is explained here[^].

I've don't exactly what the way to convert the code from vb to c#,
bt i hav done through this http://www.developerfusion.com/tools/convert/vb-to-csharp/
it gives u correct code.......

I think that you can use this code converter
Telerik Code Converter

As many have pointed out, there are many VB.Net < = > C# converters out there, some better than others, some free, some commercial.
The standard rule is this...

They will convert most code from one to the other, but none of them are perfect, and you will still need to go through and debug the converted code.