a delicious C++ question 4 you😉

Question

What is the output of this code？
voidf(int& x){
cout<<x++;
x=2;
}
int main(){
int a=3;
int& b=a;
f(a);
cout<<b;
}
My answer is 33 but the official answer is 32, why？[ I 'd like to give you a piece of virtual ( void）cake 🍰]

Answer 1

@ Ace, thank you very much for your good explanation 👍😉

Answer 2

Thank you for your detailed answer ，at last I got it😊

Answer 3

@Ace your explanation is right one point! Here, have some virtual cake ( 🍰).

Answer 4

I'll try to trace what's happening in a way you can understand.

Let's keep track of what each variable is and when changes occur.

Initially, a = 3 and b's reference points to a.
Now f(a) runs...
a is still 3 when cout<<a++ runs, as a++ executes after the cout. so a = 3, b references a, so b=3.
Then a is changed to 2, and recall that b is a reference to a, so any changes to a affect b. a=2, b=2.
The function is over now and b is now printed, so a 2 is outputted to the console.

Final result: 32

Answer 5

void error not mentioning
your output is 3 and after that, you added (4)
then reassign x to be 2 which is the main function
your final answer is 32
https://babasupport.org/printer/hitachi-customer-service/39

Answer 6

easy
no problem at all

Answer 7

i want to eat