Does it make a difference to check null on either side of conditional?

Question

I have seen both

if(something == null)

and

if(null == something)

Does it make a difference in which order this null check happens? I do not see a difference in functionality but would love to know if there is reasoning behind it.

It's like 2 == 3 and 3 == 2, the side do not affect the outcome. — Pierre-Luc Pineault, Jun 16 '13 at 23:53

score 7 · Accepted Answer · edited May 23 '17 at 11:50

7

This is legal in C# and is colloquially known as a Yoda Condition. Many people in the C/C++ world like this because it guards at compile time against replacing == with = by accident. However, it has fallen out of favor in C# due to the fact the compiler will flag it (the single =) as an error in that instance (so long as it's not a boolean eval).

edited May 23 '17 at 11:50

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answered Jun 16 '13 at 23:56

Jesse C. Slicer

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I prefer this syntax, but I could see why people find it confusing. I just hate when I see this: if(true == myVariable) { } – Karl Anderson Jun 17 '13 at 00:42

score 5 · Answer 2 · answered Jun 16 '13 at 23:53

Some programmers prefer to put the constant on the left side of an equality operator to avoid accidents (a typo of = instead of ==). In the second example, having the = typo would introduce a compiler error, which is easy to fix, whereas in the first example such a typo may introduce a bug that is very difficult to find.

This practice comes directly out of C and C++ programming style. I don't know whether it would affect C#. If it's no longer relevant, then it's more likely to be a habit rather than a strategy.

Does it make a difference to check null on either side of conditional?

2 Answers2