Hey friends !please explain this code below

Question

iostream>
using namespace std;

int main(){
int a[3]={9,3,4};
for(int i =2;i>0;i--){
a[0]-=a[i];
}
cout<<a[0];

return 0;

}
//output 2 ?

Answer 1

The for loop runs 2 iterations, in the first iteration, the first element (9) is decremented by third element (4) which changed first element's value to 5. In second iteration, the first element (5) is decremented by second element (3) which then changed first element's value to 2.

Hth, cmiiw

Answer 2

Just to add what Ipang said, remember that arrays start at 0, so the first element (item) in your array is a[0].

So, the line

a[0] -= a[i];

Takes the value of a[0] which is 9 and reduces it by the value of a[i].

The value of 'i' starts at 2 in the loop, so you essentially have
1st time in loop
a[0] = 9 - 4;

Then
2nd time in loop
a[0] = 5 - 3;

Answer 3

Thanks Ipang and Duncan

Answer 4

You're welcome Albert, glad if it helps : )