Different between ToString(),Convert.Tostring() and (string)variable in C#

Question

Different between [ToString()],[Convert.Tostring()] and [(string)variable] in C#

Answer 1

int A =0;
MessageBox.Show(A.ToString());
MessageBox.Show(Convert.ToString(A));

Here both the methods are used to convert the string but the basic difference between them is: "Convert" function handles NULLS, while "i.ToString()" does not it will throw a NULL reference exception error. So as good coding practice using "convert" is always safe. (string)casting is only to convert string and objects.

Let's see another example:

    string s;
    object o = null;
    s = o.ToString();
    //returns a null reference exception for s.

    string s;
    object o = null;
    s = Convert.ToString(o);
    //returns an empty string for s and does not throw an exception.

 static void Main(string[] args)
        {
            try
            {
                string s;
                object o = null;
                s = (string)o;
                Console.WriteLine(s);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }


            Console.ReadKey();  
        }
 //returns an empty string for s and does not throw an exception.