What's the reasoning behind putting constants in if statements first?

Question

I was looking at some example C++ code for a hardware interface I\'m working with and noticed a lot of statements along the following lines:

if ( NULL == pMsg )          


        

Answer 1

They said, "to prevent mixing of assignment and comparison".

In reality I think it is nonsense: if you are so disciplined that you don't forget to put constant at the left side, you definitely won't mix up '=' with '==', would you? ;)