Confused by 'break' in the official documents

[buran]

so ran them both without the break statements and the output is the same!

That is not true, the output is different.

First snippet, with break:

Output:
4 equals 2 * 2.0
6 equals 2 * 3.0
8 equals 2 * 4.0
9 equals 3 * 3.0

First snippet, without break:

Output:
4 equals 2 * 2.0
6 equals 2 * 3.0
6 equals 3 * 2.0
8 equals 2 * 4.0
8 equals 4 * 2.0
9 equals 3 * 3.0

There are 2 extra lines.

break serve to break out (i.e. terminate the execution) of the loop early. In the example - 6 is evenly divisible by 2, so there is no need to continue searching for other divisors, obviously it's not prime number.


Now, in the second snippet you have also extra else clause. If the loop exection finishes normally (i.e. not from break) this will be executed.

Output:
2 is a prime number
3 is a prime number
4 equals 2 * 2
5 is a prime number
6 equals 2 * 3
7 is a prime number
8 equals 2 * 4
9 equals 3 * 3

if not clear, look at this step by step execution