vector of vector size

[mickey]

hi, I need to retrieve this (but i wouldn't like use 'i'):

vector < vector <double> >* e
e->at(i).size()
e->at(0).size() //it's the same

vector < vector <double> >* e
e->at(i).size()
e->at(0).size() //it's the same

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In this case the vector contains n vectors which must have the same size!
so e->at(0).size() and e->at(1).size() and e->at(n).size() are the same value;
But I don't like use (0) the reach the size.

How can I do?
and: maybe it isn't necessary use a vector of vector !?

thanks