int Number = 6;
int x = Number--;
// At this point Number is 5, and x is 6.
int Number = 6;
int x = --Number;
// At this point Number is 5, and x is 5.
The main issue why I couldn't find myself to reply sooner is:
1. Timing
2. Topic name
Be a bit more explicit, the issue in your program is not the output itself, but is the Increment/Decrement operator.