Question

Possible Duplicate:
Why does one often see “null != variable” instead of “variable != null” in C#?

Is there any difference between checking for null in the following ways:

object x;
// more code to work on x
if (null == x)
   return;

and

object x;    
// more code to work on x
if (x == null)
   return;

I think its just a style preference and there is nothing wrong (code logic or performance) with it but wanted to check. I think the later is easier to read but my colleague insists on writing it the first way. It drives me nuts. Thanks.

Answer 1

I think its just a style preference

It is, it comes from the C/C++ world where apparently this error is very common:

if (x = null)

So instead of a comparison it’s an assignment which introduces a potentially subtle bug. That’s why they use

if (null = x)

which throws a compiler error.

In C#, both are illegal, so

if (x == null)

seems to be the common form.