而且这里即时用reserver保留了空间,push_back也会进行额外的条件检查,而这种检查是operator[]不会有的。此外,而且push_back增加size值(reserve 只设置capacity),因此每次都会更新。 简而言之,push_back做的比做的多operator[]——这就是为什么它更慢(更准确)。 这里stackoverflow线程还讨论更多的扩展点,一个比较有...
push_back:不允许追加字符数组。 实现: // CPP code for comparison on the basis of// Appending character array#include<iostream>#include<string>usingnamespacestd;// Function to demonstrate comparison among// +=, append(), push_back()voidappendDemo(string str){charch[6]={'G','e','e...
std::stack::push std::stack::size std::stack::stack std::stack::swap std::stack::top std::swap(std::array) std::swap(std::deque) std::swap(std::forward_list) std::swap(std::list) std::swap(std::map) std::swap(std::multimap) std::swap(std::multiset) std::swap(std::prio...
push_back():不可以使用push_back()来追加字符数组。 // CPP code for comparison on the basis of // Appending character array #include <iostream> #include <string> using namespace std; // Function to demonstrate comparison among // +=, append(), push_back() void appendDemo(strin...
std::vector<int> v; v.push_back(1); v.push_back(2); v.push_back(3); for (int i : ...
emplace_back比push_back的效率更高,但是使用emplace_back的代码健壮性不如push_back,例如 点击查看代码 std::vector<int> vec1; vec1.push_back(3); vec1.emplace_back(5);std::vector<std::vector<int>> vec2;//vec2.push_back(3);// 报错vec2.emplace_back(5);// vec2 = { {0,0,0,0,0...
运行的时候在push_back那一句报如下的错误: Unhandled exception at 0x50C031CA (msvcr120d.dll) in Test15.exe: 0xC0000005: Access violation reading location 0x391F9350.试了一下,如果不是push_back自定义的struct,而是push_back一个内置类型(比如int,string)就不会报错.到底是怎么回事那? 请指教. 谢谢 ...
std::stack::push std::stack::size std::stack::stack std::stack::swap std::stack::top std::swap(std::array) std::swap(std::deque) std::swap(std::forward_list) std::swap(std::list) std::swap(std::map) std::swap(std::multimap) ...
std::array::at std::array::back std::array::begin std::array::cbegin std::array::cend std::array::crbegin std::array::crend std::array::data std::array::empty std::array::end std::array::fill std::array::front std::array::max_size std::array::operator[] std::array::rbegin...
push_back(0); } The invalid access happens here: My guess for the reason of the error is that _Alloc_proxy of std::vector is not called for global, and therefore zero-initialized, std::array of std::vector.C++web This issue is read only, because it has been in t...