Depending where the increment line is, the output is different, could someone explain why? Much appreciated

Question

https://code.sololearn.com/cEpkw20HZLxh/?ref=app

Answer 1

1st case:
while (num < 6) {
num = num + 3;
cout << "Number: " << num << endl;
}

Output: 4 7

How it works:
Initially num was 1. Inside the loop, the value is added with 3 first, then printed.
So 1+3 = 4, then print it.
Again, 4+3 = 7, then print it.

2nd case:
while (num < 6) {
cout << "Number: " << num << endl;
num = num + 3;
}

Output: 1 4

How it works:
Initially num was 1. Inside the loop, the value is printed first, then 3 has been added with last value.
So num = 1, print 1, change num to 4
Again, num = 4, print 4, change num to 7. But since 7 makes the condition false, 7 won't be printed.

Answer 2

in a "while loop" the compiler reads your cods from the beginning, so order is important.For example it does "num=num+3" first before it prints the integer, but in the second one it first prints the integer then does the "num=num+3".

Answer 3

in line 8 you add before output, in line 10 after output. so your output is shifted by one cycle.
a) num = 1, compare, num=4, output, compare, num=7, output, compare, end
b) num=1, compare, output, num=4, compare, output, num=7, compare, end