Like many programmers, I have a Common Function Library containing generic methods I use over and over again. Here is one of them.

/// <summary>
/// Checks a variable to make sure it has value (isn't null or a zero-length string once trimmed).
/// </summary>
/// <param name="o">variable to test.</param>
/// <returns>true if the variable has a value.</returns>
public static bool HasValue(object o)
{
if ( o == null )
{
return false;
}

if ( o == System.DBNull.Value )
{
return false;
}

if ( o is String )
{
if ( ( (String)o ).Trim() == String.Empty )
{
return false;
}
}

return true;
}

I use this often to test if a variable or object exists and if it has any value. This is an easy way to avoid NullReferenceExceptions or other errors that would crop up if an object is null — BEFORE the exception is thrown.