How does the Computer Code Execute?

1) sum = 0;

2) i = 0;

3) do {

4) i = i + 1;

5) sum = sum + i;

6) } while (i < n);

Line 1) variable sum gets a value 0;

Line 2) variable i gets 0;

Line 3) mark the beginning of a while-loop;

Line 4) replace the value of variable i by its old value (0) plus 1. I.e., i = 1;

Line 5) replace the value of sum by its old value (0) + current value of i,

i.e., sum = 0+1=1.

Line 6) is i < 3? yes, since I=1, so go back to line 4);

Line 4) value i increased by 1 to 2;

Line 5) value sum becomes 1 + 2 = 3;

Line 6) is i < 3? yes, since i = 2, go back to Line 4);

Line 4) i becomes 2 +1 = 3;

Line 5) sum becomes 3 + 3 = 6;

Line 6) is i < 3? no, since i = 3. Program stops.