General function for all value types in class

Question

I'm trying to accomplish the following within a class:

public void Test(var input)
{
    WriteToFile(input.ToString());
}

private void WriteToFile(string input)
{
    .....
}

But the 'var' statement can not be used within a class. So I'm wondering what the easiest way is to accomplish the same thing as above.

One solution would be to create a function for each value type, but that must be more trouble than necessary:

public void Test(string input)
{
    WriteToFile(input);
}

public void Test(int input)
{
    WriteToFile(input.ToString());
}

public void Test(double input)
{
    WriteToFile(input.ToString());
}

private void WriteToFile(string input)
{
    .....
}

EDIT: When giving it some more thought I understood that this wasn't really the answer to my problems. I'm posting a new question that has more thought behind it. I'm not gonna delete this question though since someone else might find this usefull.

Answer 1

Just pass object and call ToString() on it:

public void Test(object input)
{
    WriteToFile(input.ToString());
}

Answer 2

public void Test<T>(T input)
{
    WriteToFile(Convert.ToString(input));
}