normal and random access iterator

This is a discussion on normal and random access iterator within the C++ Programming forums, part of the General Programming Boards category; Hi I have a question regarding to iterators I have a class which looks like this Code: class CardItem{ public: ...

  1. #1
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    normal and random access iterator

    Hi

    I have a question regarding to iterators

    I have a class which looks like this

    Code:
    class CardItem{
    	public:
    		CardItem(){
    			Card newcard(1, JOCKER);
    			subdeck.push_back(newcard);
    			Card newcard2(2, DIAMOND);
    			subdeck.push_back(newcard2);
    		};
    		virtual ~CardItem(){};
    		
    		virtual void Shuffle(int flag);
    		//virtual void Sort(int flag);
    		vector<Card> Take(const int start, const int end);
    		/*
    		void Add(vector<Card> addon, int pos);
    		*/
    	protected:
    		bool fcompare(const Card& i, const Card& j);
    	private:
    		vector<Card> subdeck;
    		vector<Card> takeout;
    };
    and the implmentation of the vector<Card> Take() function is
    Code:
    vector<Card> CardItem::Take(const int start, const int end){
    	vector<Card>::iterator vStart = &subdeck[start];
    	vector<Card>::iterator vEnd = &subdeck[end];
    	for(int i = start; i <= end; ++i){
    		takeout[i-start] = subdeck[i];
    	}
    	subdeck.erase(vStart, vEnd);
    }
    the Card class is
    Code:
    class Card{
    	public:
    		Card(int val, suit_t suit);
    		virtual ~Card(){};
    		int getVal() const {return val;};
    		suit_t getSuit() const {return suit;};
    	private:
    		int val;
    		suit_t suit;
    		
    };
    when I compile my code, the error message says

    cardItem.cpp:20: error: conversion from `Card*' to non-scalar type `__gnu_cxx::__normal_iterator<Card*, std::vector<Card, std::allocator<Card> > >' requested
    cardItem.cpp:21: error: conversion from `Card*' to non-scalar type `__gnu_cxx::__normal_iterator<Card*, std::vector<Card, std::allocator<Card> > >' requested


    I understand that erase() requires two random access iterators, is there anyway to cast the normal iterator into random access iterator?

    Cheers
    Kai

  2. #2
    The larch
    Join Date
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    Posts
    3,573
    Iterators are obtained with the begin() and end() method. They are not just pointers.
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  3. #3
    ZuK
    ZuK is offline
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    Quote Originally Posted by hka26 View Post
    I understand that erase() requires two random access iterators, is there anyway to cast the normal iterator into random access iterator?
    A vector::iterator is a random access iterator. So you must have understood something wrong.
    Kurt

  4. #4
    Cat without Hat CornedBee's Avatar
    Join Date
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    Posts
    8,892
    Did you mean to do something like this? Because I notice that you specify a return type for Take but you don't actually return something.

    Code:
    vector<Card> CardItem::Take(const int start, const int end){
    	vector<Card>::iterator first = subdeck.begin() + start, last = subdeck.begin() + end;
    	vector<Card> res(first, last);
    	subdeck.erase(first, last);
    	return res;
    }
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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