I don't understand the solution of this exercise

Question

I am doing an exercise on Practiceit.edu and I have some trouble. The exercise is writing of the following codes:

int total = 25;
for (int number = 1; number <= (total / 2); number++ ) {
    total = total - number;
    System.out.println(total + " " + number );
}

My output is

24 1
22 2
19 3
15 4
10 5
4 6
-3 7
-11 8
-20 9
-30 10
-41 11
-53 12

because i think that number starts at 1 and finish at 12 (number <= (total / 2)). However, the result is

24 1
22 2
19 3
15 4
10 5

I don't understand this result, so can you help me explain it?

Answer 1

The problem is that you are changing the value of total which will be re-evaluated every-time in your loop

try

int total = 25;
int total2 = total;
for (int number = 1; number <= (total / 2); number++ ) {
    total2 = total2 - number;
    System.out.println(total2 + " " + number );
}

output

24 1
22 2
19 3
15 4
10 5
4 6
-3 7
-11 8
-20 9
-30 10
-41 11
-53 12

Answer 2

This is because your total is reducing more and more each time you iterate.

total = total - number;

Ie:

//1st iteration
25 - 1 = 24; // outputs 24 1

// 2nd iteration
24 - 2 = 22 // outputs 22 2

// 3rd iteration
22 - 3 = 19 // outputs 19 3

// 4th iteration
19 - 4 = 15 // outputs 15 4

// 5th iteration
15 - 5 = 10 // outputs 10 5

Etc.

What are you trying to do?

Answer 3

During the final iteration that is printed, total is 10 and number is 5. Once the for loop continues, number increases by 1 and total decreases to 4. The comparison is made between total = 4 / 2 = 2 and number = 6. This result is not printed since the comparison is already made. Thus, you exit the for loop.

Answer 4

The condition used in the for loop says the number is less than or equal to (half of) total

number <= (total / 2)

The last line where that is true is 10 5

Everything after that doesn't satisfy the condition.