One code, 2 different results C# vs C++

The difference lies in handling of extended assignment
operators such as +=, -=, /= etc etc in different
languages such as Java or C# versus C++.
In Java it is handled like this...
<variable><op>=<expression> the symantics for this are
<variable> = (<type>)(<variable><op>(<expression>))
Note, in Java the <variable> is evaluated just once upon
entry v/s C++ where the latest values for the variable is
used, hence the difference. Please refer to "Programmers
Guide to Java Certification by Khalid Mughal, page 53" for
reading up on Java's handling of Extended Assignment
operators. I do not think it is operator precedence.
Extended assignment operators have same precedence as
assignment operators which is the lowest in the precedence
table, --, ++ are ranked much much higher than assigment
operators....