Validating function arguments?

Question

On a regular basis, I validate my function arguments:

public static void Function(int i, string s)
{
  Debug.Assert(i > 0);
  Debug.Assert(s != null);
  Debug.Assert(s.length > 0);
}

Of course the checks are "valid" in the context of the function.

Is this common industry practice? What is common practice concerning function argument validation?

Answer 1

The accepted practice is as follows if the values are not valid or will cause an exception later on:

if( i < 0 )
   throw new ArgumentOutOfRangeException("i", "parameter i must be greater than 0");

if( string.IsNullOrEmpty(s) )
   throw new ArgumentNullException("s","the paramater s needs to be set ...");

So the list of basic argument exceptions is as follows:

ArgumentException
ArgumentNullException
ArgumentOutOfRangeException