Increment operator used in a while loop's condition

Question

#include <iostream>
using namespace std;

int main()
{
int x = 3;
while (x++ < 10) {
x+=2;
}
cout<<x;
return 0;
}

// outputs 13

How did we get to 13?

My thought process:

run 1 gives 6 (Because x++ in the condition turns x=3 into x=4. Statement x+=2 thus gives 6)
run 2 gives 9 (Because x++ in the condition turns x=6 into x=7. Statement x+=2 thus gives 9)
run 3 is a no go because x++ in the condition turns x=9 into x=10, making the condition false and stoping the while loop...

Answer 1

in while loop, x++ is a post increment, which means when the condition is checked , after that the value of x will change..
so after while(3< 10) x becomes 4 and x+=2 will give x= 6 ,
and after while(6 < 10) x becomes 7 and x+=2 will give x= 9,
and after while(9< 10) x becomes 10 and x+=2 will give x= 12 and next cond fails for x<12
but x++ will happen making it 13

Answer 2

x++ post incrementing values each time that means in the third scenario the comparison was among 9 < 10 where 10 obviously is greater. so, the code runs again two times

Answer 3

For post increment, the incrementation happens even though the condition is false.

Thank you @codemonkey.

Answer 4

Solus The condition wasn't false when while loop compared it. x is incremented afterward that means it was 9 otherwise while loop didn't run and the output would be 10