2
main()
{
   int k=35;
   printf("%d %d %d",k==35,k=50,k>40);
}

The output of this code is 0 50 and 0 I couldn't understand why? Because I have learnt that priority of assignment operator is the least and the releational operator priority is more that that then how this kind of output has come please explain?

pratik jain
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  • ⟼Remember, it's always important, *especially* when learning and asking questions on Stack Overflow, to keep your code as organized as possible. [Consistent indentation](https://en.wikipedia.org/wiki/Indentation_style) helps communicate structure and, importantly, intent, which helps us navigate quickly to the root of the problem without spending a lot of time trying to decode what's going on. – tadman Apr 26 '21 at 03:13
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    Hint: The order in which the arguments are evaluated is not required to be in any particular order. – tadman Apr 26 '21 at 03:14
  • related/dupe: https://stackoverflow.com/questions/949433/why-are-these-constructs-using-pre-and-post-increment-undefined-behavior – NathanOliver Apr 26 '21 at 03:20
  • Precedence is for disambiguation. There's no ambiguity between the assignment and relational operators here. If you had something like `k = 50 == 35`, that would be up to precedence to make it either `(k = 50) == 35` or `k = (50 == 35)`. – chris Apr 26 '21 at 03:23
  • Does this answer your question? [Why are these constructs using pre and post-increment undefined behavior?](https://stackoverflow.com/questions/949433/why-are-these-constructs-using-pre-and-post-increment-undefined-behavior) – Nate Eldredge Apr 26 '21 at 04:52

1 Answers1

1

There is no fixed order defined by the C standard. A compiler may choose to evaluate either left-to-right or right-to-left. So in your case, the compiler is evaluating the expression from right to left. And as you know that == generates the output as a boolean value. So the first evaluation done by the compiler is 35>40 which is False(0) and k=50 so simply assignment is done and finally, k(50) is compared with 35 which results in False(0).

Therefore your output is 0 50 0.

I hope it cleared your doubt..

Abhishek Jaiswal
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  • Left-to-right and right-to-left are not the only options for argument evaluation order. Further, they do not have to be in order at all; a compiler may interleave parts of the argument expressions. And the assignment part of an assignment expression is a side effect that may occur at a different time from the evaluation of the assignment expression. – Eric Postpischil Apr 26 '21 at 06:33