Please explain the process

Question

#include <iostream>
using namespace std;

int main() {
int a,b,ans;
ans=0;
a=2;
b=a*2;
for(int i=1;i<=3;i++)
{
b*i;
ans=ans+b;
}
cout <<ans;
return 0;
}

Answer 1

b = b * i;

will achieve what you are trying to do.

Answer 2

thanks @chaoticdawg and @hatsyrei

Answer 3

Before the loop:
ans is set to 0
a is set to 2
b is set to a * 2, so b is 4

The for loop loops 3 times.
in the body of the loop:
b*i; just multiplies b * i, but it doesn't save the result back into any variable, so it has no effect. b will remain 4 throughout the program.
1st loop
ans = ans + b (0+4) = 4
2nd loop
ans = ans + b (4+4) = 8
3rd loop
ans = ans + b (8+4) = 12

ans is 12 when the loop finishes and is output to the console.

Answer 4

That means if I needed to increment the value of b inside the for loop, I would need another variable to store the incremental value of b ??