Why B =2 in answer?

Question

void f(int &x){
cout<<x++;
x=2;
}
int main(){
int a=3;
int &b=a;
f(a);
cout<<" b"<<b;
}

Answer 1

When you do
int &b = a;
b is simply an alias for a. (i.e. b is a).
a gets passed into f() via reference, and the value is altered to 2.

Answer 2

because it is passed by reference so its value can be modified by the function f

Answer 3

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