Checking for null, which is better? “null ==” or “==null” [duplicate]

Answer 1

In c# there's no difference. It's an old habit from C/C++ developers to avoid a common bug where this is correct syntax:

if(o = null)

In C# that wouldn't compile but in C and C++ it would, leaving you with a pretty nasty bug. Therefore, many people got used to doing

if(null == o)

Answer 2

Irrelevant for C#, this is from C. See this question for a discussion.

Answer 3

it's an old habit to prevent you from typing if (o = null). if (null = o) is a syntax error. kind of pointless in C#, because null values aren't ever coerced into booleans.

Answer 4

The latter is a holdover from the C/C++ days, where it was possible to accidentally assign a value instead of compare. C# won't allow you to do this, so either/or is acceptable (but I find the former more readable).

Answer 5

I work with Java ..and I do have the habit of having constants on the LHS for all commutative comparisons.

"name".equals(name)

 null == obj

"55".compareTo(numString)

etc..Just avoiding unnecessary NullPointerExceptions...