std :: sort无法识别迭代器类别

Question

我实现了一些矢量迭代器:

class iterator : public std::iterator<std::input_iterator_tag, int> {
    Vector<T> *vector;
    size_t position;

public:
    iterator(Vector<T> *vector_, size_t idx) {...};
    iterator(const iterator &it) {...};
    friend bool operator == (const iterator &a, const iterator &b) {...};
    friend bool operator > (const iterator &a, const iterator &b) {...};
    friend bool operator < (const iterator &a, const iterator &b) {...};
    friend bool operator >= (const iterator &a, const iterator &b) {...};
    friend bool operator <= (const iterator &a, const iterator &b) {...};
    friend bool operator != (const iterator &a, const iterator &b) {...};
    iterator &operator = (const iterator &b) {...};
    T operator * () {...};
    iterator &operator ++ () {...}
    iterator &operator -- () {...}

    std::ptrdiff_t operator - (const iterator &b) const {...}
};

但是,因为调用std::sort(vector.begin(), vector.end())输出错误的原因no operator +=,这就是事实std::sort对待我的迭代器就像随机访问一样.为什么？

Answer 1

std::sort要求RandomAccessIterators.虽然它可能认识到你给了它不兼容的迭代器,但它仍然无效.