vector

Yes. See here.

what is different between capicity() and size()
they seem to make same thing.

Quote:

Original post by luasitdown what is different between capicity() and size() they seem to make same thing.

size() is the number of elements currently being held in a constructed state.
capacity() is the number of elements that the vector has memory for, and that it can be grown to without a reallocation (and thus without invalidating any iterators). If you try to access between size() and capacity(), you'll be accessing uninitialized regions of memory!!! No constructors have been called for this region, no destructors will be called for this region if the vector goes out of scope. Constructors are only called, and destructors will only be called, for up to size().

You probably don't need to use capacity().