I dont understand how dis code fives me 4

Question

int a=3
int b=2
b=a++
cout<<++b.
and ans is 4?

Answer 1

b = a++ assigns b to the current value of a which is 3. After the assignment is done, a is incremented. ++b on the other hand increments b to 4 and returns that value. You may want to look up post increment and pre increment to learn more.

Answer 2

b=a++
So now b=a, which is 3, and you added one to a, so it's 4. ++b is 1+b which is 1+3, so the answer is 4.