Triangular+Triangular-iterator+iterator-overflow.zip

#include "Triangular.h" #include <iostream> #include <vector> #include <algorithm> using namespace std; vector<int> Triangular::_elems; // int Triangular::_initial_size = 8; // Triangular::Triangular() // { // _length = 1; // _beg_pos = 1; // _next = 0; // } // Member initialization list(成员初始化列表) Triangular::Triangular(int len, int bp) : _name("Triangular"), _length(len > 0 ? len : 1), _beg_pos(bp > 0 ? bp : 1) { _next = _beg_pos - 1; int elem_cnt = _beg_pos + _length - 1; if (_elems.size() < elem_cnt) gen_elements(elem_cnt); } // 给定某值，依据该值是否在数列内而返回true或false。 bool Triangular::is_elem(int value) { if (!_elems.size() || _elems[_elems.size() - 1] < value) gen_elems_to_value(value); vector<int>::iterator found_it; vector<int>::iterator end_it = _elems.end(); found_it = find(_elems.begin(), end_it, value); return found_it != end_it; } void Triangular::gen_elements(int length) { if (length < 0 || length > _max_elems) { cerr << "Triangular Sequence: oops: length too large " << length << " -- exceeds max size of " << _max_elems << endl; return; } if (_elems.size() < length) { int ix = _elems.size() ? _elems.size() + 1 : 1; for (; ix <= length; ++ix) { _elems.push_back(ix * (ix + 1) / 2); } } } void Triangular::gen_elems_to_value(int value) { int ix = _elems.size(); if (!ix) { _elems.push_back(1); ix = 1; } while (_elems[ix - 1] < value && ix < _max_elems) { ++ix; _elems.push_back(ix * (ix + 1) / 2); } if (ix == _max_elems) cerr << "Triangular Sequence: oops: value too large " << value << " -- exceeds max size of " << _max_elems << endl; } int Triangular::elem(int pos) const { return _elems[pos - 1]; } bool Triangular::next(int &value) const { if (_next < _beg_pos + _length - 1) { // 更改了class object _next的内容。 value = _elems[_next++]; return true; } return false; } Triangular &Triangular::copy(const Triangular &rhs) { if (this != &rhs) { _length = rhs._length; _beg_pos = rhs._beg_pos; _next = rhs._beg_pos - 1; } return *this; } istream & operator>>(istream &is, Triangular &rhs) { char ch1, ch2; int bp, len; // 假设输入为（3，6）6 10 15 21 28 36 // 那么ch1 == '('，bp == 3，ch2 == ','，len == 6。 is >> ch1 >> bp >> ch2 >> len; // 设定rhs的三个data member rhs.beg_pos(bp); rhs.length(len); rhs.next_reset(); rhs.gen_elements(bp + len - 1); return is; }