std::vector<T,Allocator>::reserve voidreserve(size_type new_cap); (C++20 起为constexpr) 增加vector的容量(即vector在不重新分配存储的情况下能最多能持有的元素的数量)到大于或等于new_cap的值。如果new_cap大于当前的capacity(),那么就会分配新存储,否则该方法不做任何事。
push_back(n); } std::cout << "not using reserve: \n"; { std::vector<int, NAlloc<int>> v1; for (int n = 0; n < max_elements; ++n) { if (v1.size() == v1.capacity()) std::cout << "size() == capacity() == " << v1.size() << '\n'; v1.push_back(n);...
swap,std::swapend() clear,operator=,assignAlways. reserve,shrink_to_fitIf the vector changed capacity, all of them. If not, none. eraseErased elements and all elements after them (includingend()). push_back,emplace_backIf the vector changed capacity, all of them. If not, onlyend(). ...
swap、std::swapend() clear、operator=、assign始终 reserve、shrink_to_fitvector 更改容量时全部失效。否则不失效。 erase被擦除元素及之后的所有元素(包括end())。 push_back、emplace_backvector 更改容量时全部失效。否则只有end()。 insert、emplacevector 更改容量时全部失效。否则只有在或于插入点后者(包括...
swap,std::swapend() clear,operator=,assignAlways. reserve,shrink_to_fitIf the vector changed capacity, all of them. If not, none. eraseErased elements and all elements after them (includingend()). push_back,emplace_backIf the vector changed capacity, all of them. If not, onlyend(). ...
Insertion or removal of elements in the beginning or in the middle – linear in the number of elements inserted/removed plus the distance to the end of the vector:𝓞(n). Iterator invalidation std::inplace_vectoriterator invalidation guarantees differ fromstd::vector: ...
Prefer using C++ string (std::string or std::wstring) to C-string const char*, char* and so on. Use standard STL containers std::vector, std::deque, std::map, std::unordered_map instead of custom non-standard containers. Instead of using heap-allocated arrays (A* pArray = new A[...
#include <iostream> int main() { std::cout << "Hello Quick Reference\n"; return 0; }编译运行$ g++ hello.cpp -o hello $ ./hello Hello Quick Reference变量int number = 5; // 整数 float f = 0.95; // 浮点数 double PI = 3.14159; // 浮点数 char yes = 'Y'; // 特点 std:...
older internal code used vector::reserve () and operator[] to populate the vector. This led to an incorrect value being returned from vector::size() and an uncertainty about whether or not the vector has a trailing NULL entry (needed by JS_DefineFuncti ons()). It is a wonder that ...
std::vector definiert in Header<vector> template< classT, classAllocator=std::allocator<T> >classvector; std::vectorist ein sequentieller Container, der Arrays dynamischer Größe kapselt. Die Elemente werden zusammenhängend gespeichert, was bedeutet, dass auf die Elemente nicht nur durc...