Wrong calculation?

Question

C++ / C#

I can't understand why the constructions produce different results, depending on the compiler. Checked on JS and Java, give the same correct result (as I think):
JS:

Java:

Link to Java example: goo.gl/HD223t
And here are the results of C ++:
MSVCC 2015

cpp.sh (gcc 4.9.2)

WTF?

Answer 1

For C++, this construct violates the language standard and leads to undefined behavior. You can't write like that in C++.

Answer 2

give the same correct result.

equally correct result for java, because the order of evaluation of the value of expressions in java is strictly defined for any expression, see https://docs.oracle.com/javase/specs/jls/se7/html/...
C++ -- this is a different language, you can write an expression like yours in it, the meaning of which is not defined by the standard and may vary depending on the compiler, optimization options and the phase of the moon. See https://ru.wikipedia.org/wiki/%D0%A2%D0%BE%D1%87%D...

Answer 3

Even girls write about this: alenacpp.blogspot.ru/2005/11/sequence-points.html ))