C++ code what is the answer of y

Question

int a=5,y;
y=++a + a++ + ++a;
cout<<y;

Answer 1

21 is perfect answer given by Netkos Ent and also compiler to

Answer 2

can you define me how?

Answer 3

thanks now i am satisfied.

Answer 4

21

Answer 5

Sure.

++a and ++a make a 7. Add the one from a++. 7 + 7 + 7 = 21

Answer 6

i was going to say 19 (6 +6+7) but i am wrong and i see why...

Answer 7

Not sure why Baptiste got downvotes since he is correct, it is undefined.

GCC and VC++ will indeed print out 21 here but clang prints 20.

Not sure where people keep learning this stuff but you should never use it again.

Answer 8

Thanks for your support @Dennis !

They keep learning that because SoloLearn challenge has questions like that. The answer is the way the SoloLearn compiler (GCC) defined it, not the way all compilers defined it.

Answer 9

such questions should not be used in challenges at all, or the answer is to be "undefined" and "compiler dependent".

Answer 10

It is compiler dependant, so neither @Netkos or @Kostas are right or wrong

Answer 11

No @Md Shakif, it is undefined behavior

Answer 12

what is the right answer?