C# Antipatterns

Question

Rethrowing the exception incorrectly. To rethrow an exception :

try
{
    // do some stuff here
}
catch (Exception ex)
{
    throw ex;  // INCORRECT
    throw;     // CORRECT
    throw new Exception("There was an error"); // INCORRECT
    throw new Exception("There was an error", ex); // CORRECT
}

GC.Collect() to collect instead of trusting the garbage collector.

I see this one way too much, both in Java and C#...

if(something == true){
  somethingelse = true;
}

with bonus points if it also has

else{
  somethingelse = false;
}

using Microsoft.SharePoint;

'nuff said

I see following code a lot:

if (i==3)
       return true;
else
       return false;

should be:

       return (i==3);