If statements that are nested and the "&&" operator

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Is there "any" difference in performance between these two?

if(a() && b() && c() && d())
   doSomething();


if(a())
   if(b()) 
      if(c())
         if(d())
            doSomething();

What I have tried:

For example, if a() returns 0, would the first if statement continue to run b(), c(), and d()? Or will it behave similarly to the second nested if statement?
Before posting this code I've done some research and read an article on https://www.scaler.com/topics/c/nested-if-else-statement-in-c/.

Posted 17-Jul-22 23:17pm

Syed Mubashshir Hasan

Updated 18-Jul-22 0:16am

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Rick York 18-Jul-22 11:15am

The only real difference is there is no guarantee of the order of evaluation of the functions with && operators while there is with the nested conditional expressions.

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CPallini · Answer 1 · 2022-07-18T00:16:00

Solution 3

They are the same, see Short-circuit evaluation - Wikipedia[^].

Posted 18-Jul-22 0:16am

CPallini

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Patrice T 18-Jul-22 6:28am

+5 The link I was looking for.

CPallini 18-Jul-22 6:30am

Thank you.

honey the codewitch · Answer 2 · 2022-07-17T23:35:00

I think it would depend on the compiler. I imagine GCC and clang would optimize the second form into the first form as long as there were no other statements between the ifs. You can check it yourself though (for any major compiler) using godbolt.org

Edit: Actually, upon reflection my guess is both result in the second form unless each method call in the test condition is an inline-able expression.

Patrice T · Answer 3 · 2022-07-18T00:10:00

Quote:
Is there "any" difference in performance between these two?

As far as I know, there is no difference.

Quote:
For example, if a() returns 0, would the first if statement continue to run b(), c(), and d()? Or will it behave similarly to the second nested if statement?

It is the standard practice of C language for last 40 years.

If statements that are nested and the "&&" operator

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