size() << std::endl; std::cout << "After deletion: "; for (int num : vec) { std::cout << num << " "; } std::cout << std::endl; } else { std::cout << "The vector is empty, cannot delete an element." << std::e...
std::vector<int> vec; vec.push_back(6); vec.push_back(-17); vec.push_back(12); // Deletes the second element (vec[1]) vec.erase(std::next(vec.begin())); 或者,一次删除多个元素: // Deletes the second through third elements (vec[1], vec[2]) vec.erase(std::next(vec.begi...
//Method 2: use emplace_back to efficiently construct element55inside the vector container.56std::cout <<"---"<<57std::endl;58{59std::vector<Vertex>vertices;60vertices.reserve(3);61vertices.emplace_back(1,2,3);62vertices.emplace_back(4,5,6);63vertices.emplace_back(7,8,9);64}6566s...
erase的实现 iterator erase(const_iterator _Where) { // erase element at where if (_VICONT(_Where) != &this->_Get_data() || _VIPTR(_Where) < this->_Myfirst() || this->_Mylast() <= _VIPTR(_Where)) _DEBUG_ERROR("vector erase iterator outside range"); _Move(_VIPTR(_Where...
std::vector<int> v = {1,2,3,4,5};// 添加元素v.push_back(6);// 访问元素std::cout <<"Element at index 2: "<< v[2] << std::endl; std::cout <<"First element: "<< v.front() << std::endl; std::cout <<"Last element: "<< v.back() << std::endl;// 修改元素v...
将矢量的当前最后一个元素分配给要擦除的元素，然后擦除最后一个元素。这将避免大的移动，除最后一个...
delete*itPos; // free the element from memory // finally, clear all elements from the array arMyClass.clear(); } It can be argued that it is much more efficient to create all elements dynamically (with the new operator) because when iterating through the vector array, the computer will...
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因为emplace_back能够调用显示构造函数,所以传递一个裸指针并不会产生编译错误。然而,当v超出了作用域,std::unique_ptr<T>的析构函数会尝试delete类型T*的指针,而类型T*的指针并不是通过new来分配的,因为它保存的是栈对象的地址,因此delete行为是未定义的。
std::vector::pop_back Delete last element std::vector::insert Insert elements 通过在指定位置的元素之前插入新元素来扩展向量,通过插入的元素数量有效地增加容器大小。 这将导致所分配的存储空间的自动重新分配,当且仅当新的向量大小超过当前的向量容量。