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Introduction vector example elements counting fix

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Earlier created vector `["Hello", "world"]` has two elements and we try to add a third element.
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dmgawel 2015-05-21 14:30:32 +02:00
parent 7bd3bbd78e
commit e30c6d131f
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@ -150,8 +150,8 @@ of those times. As the error explains, while we made our binding mutable, we
still cannot call `push`. This is because we already have a reference to an still cannot call `push`. This is because we already have a reference to an
element of the vector, `y`. Mutating something while another reference exists element of the vector, `y`. Mutating something while another reference exists
is dangerous, because we may invalidate the reference. In this specific case, is dangerous, because we may invalidate the reference. In this specific case,
when we create the vector, we may have only allocated space for three elements. when we create the vector, we may have only allocated space for two elements.
Adding a fourth would mean allocating a new chunk of memory for all those elements, Adding a third would mean allocating a new chunk of memory for all those elements,
copying the old values over, and updating the internal pointer to that memory. copying the old values over, and updating the internal pointer to that memory.
That all works just fine. The problem is that `y` wouldn’t get updated, and so That all works just fine. The problem is that `y` wouldn’t get updated, and so
we’d have a ‘dangling pointer’. That’s bad. Any use of `y` would be an error in we’d have a ‘dangling pointer’. That’s bad. Any use of `y` would be an error in