Convert integer to binary in c#

How do you convert integer numbers to binary representation?

I'm using this code

String input = "8";
String output = Convert.ToInt32(input, 2).ToString();

But it throws an exception.

Could not find any parsable digits

Your example includes an integer expressed as a string Let's say your integer was an integer and you want to take the integer and convert it to a binary string

int value = 8;
string binary = Convert.ToString(value, 2);

Which returns 1000.