【STL】back_inserter与back_insert_iterator

最新推荐文章于 2024-11-08 02:27:47 发布

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本文详细介绍了C++标准库中的back_inserter函数。通过具体示例展示了如何使用back_inserter来向容器中添加元素，并解释了其背后的实现原理。此外还提供了使用back_insert_iterator插入元素的方法。

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back_inserter一个成员函数，返回值是back_insert_iterator, 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;