What's the rule of the length of the vowels in the word?

[Thuernkgey]

I use teach yourself swedish published in 2010 and I hit a problem with the pronunciation. It is said that all the unstressed syllables are short and the situation of the stressed syllables are changeable. It means that the vowels in stressed syllables are sometimes short and sometimes long. So what's the rule of this?

[Thuernkgey]

Thanks, guys! Useful!

[Arnauti]

Generally they're short when they are followed by two consonants, and long otherwise.

[Thuernkgey]

Do these two consonant that followed need to be in the same syllable as the vowel? Like the word 'flicka' we divide it as flic-ka.

[Arnauti]

I don't know a lot about syllables in Swedish, but ck always represents one long consonant, and the vowel before that should always be short. However, if you get two of the same consonant after each other in a composite word, like, I can't think of any good examples right now, but let's say mattid meaning mat + tid = 'food time', in those cases the vowel before the double consonants is still long.
So my take is that if they tell you to divide flicka as flic-ka, that concept of syllables isn't very useful for learning the language. (But maybe I'm missing something).

[Blehg]

No, that doesn't matter. If the vowel is followed by 2 consonants, it's usually short. Cf. kvinna, flicka, hoppa, testa, komma, etc.