back_inserter和back_insert_iterator

最新推荐文章于 2025-07-01 13:56:26 发布

转载最新推荐文章于 2025-07-01 13:56:26 发布 · 2.3k 阅读

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本文介绍了C++标准库中的back_inserter和back_insert_iterator的使用方法，并通过实例展示了如何利用它们来向容器中添加元素。这些迭代器特别适用于在容器末尾插入一系列值的场景。

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back_inserter是back_insert_iterator的一个成员函数, 本质上是push_back进行操作的, 返回值back_insert_iterator, 并实现其自增.

	std::vector<int> firstvector, secondvector;
	for (int i=1; i<=5; i++)
	{ 
		firstvector.push_back(i); 
		secondvector.push_back(i*10);
	}

	// 在firstvector向量后面加入secondvector的值.
	std::copy(secondvector.begin(), secondvector.end(), std::back_inserter(firstvector));

	std::vector<int>::iterator it;
	for ( it = firstvector.begin(); it!= firstvector.end(); ++it )
		std::cout << *it << " ";
	std::cout << std::endl;

下面是一个back_insert_iterator的例子

	std::vector<int> vec;
	for (int i = 0 ; i < 3; ++i)
		vec.push_back(i);

	std::vector <int>::iterator vIter;
	std::cout << "The initial vector vec is: ( ";
	for (vIter = vec.begin(); vIter != vec.end(); vIter++)
		std::cout << *vIter << " ";
	std::cout << ")." << std::endl;

	// Insertions can be done with template function
	std::back_insert_iterator<std::vector<int> > backiter(vec);
	*backiter = 30;
	backiter++;
	*backiter = 40;

	// Alternatively, insertions can be done with the
	// back_insert_iterator member function
	std::back_inserter(vec) = 500;
	std::back_inserter(vec) = 600;

	std::cout << "After the insertions, the vector vec is: ( ";
	for (vIter = vec.begin(); vIter != vec.end(); vIter++)
		std::cout << *vIter << " ";
	std::cout << ")." << std::endl;