#include <iostream> #include <vector> #include <functional> int main() { int number1 = 42; int number2 = 73; std::vector<std::reference_wrapper<int>> numbers = {std::ref(number1), std::ref(number2)}; for (auto& num : numbers) { num.get() += 10; // 修改原始对象的值 }...
bool great_than(int first,int second) { return first > second; } std::vector<int> data = {1,2,3,4,5}; //找到第一个大于3的元素 auto it = std::find_if(std::cbegin(data),std::cend(data),std::bind(great_than,std::placeholders::_1,3)); 考虑如下代码,实现了一个函数func在函...
__cpp_lib_containers_ranges202202L(C++23)Ranges construction and insertion for containers Example Run this code #include <iostream>#include <vector>intmain(){// Create a vector containing integersstd::vector<int>v={8,4,5,9};// Add two more integers to vectorv.push_back(6);v.push_back...
std::move - cppreference.comzh.cppreference.com/w/cpp/utility/move std::move主要使用在以下场景: C++ 标准库使用比如vector::push_back 等这类函数时,会对参数的对象进行复制,连数据也会复制.这就会造成对象内存的额外创建, 本来原意是想把参数push_back进去就行了. C++11 提供了std::move 函数来...
value < b.value; }; int main() { vector<DataPool> vec; vec.push_back(DataPool(2, 1)); vec.push_back(DataPool(5, 2)); vec.push_back(DataPool(1, 3)); std::sort(vec.begin(), vec.end(), SortCallBack); return EXIT_SUCCESS; } 这样,就相当于自定义了 struct 的排序规则,自然...
reference wrapper的一大用处就是,stl容器提供的是value语义而不是reference语义,所以容器不支持元素为引用,而用reference_wrapper可以实现。以下代码摘自http://en.cppreference.com/w/cpp/utility/functional/reference_wrapper #include<algorithm>#include<list>#include<vector>#include<iostream>#include<numeric>#inclu...
Lref + Const使用 但常量左值引用可以指向右值,因为常量引用不能去修改变量。 Const int& c_lref_a =5 ; 否则vector 的Void push_back(const value_type&val); 则不能使用 v.push_back(5) ; todo疑问: 参数为常量引用,是否会执行value_type 的构造,再把产物放进去,和直接 value_type类型做参数有什么区...
1 std::thread传入引用值需要使用std::ref std::ref的说明: Constructs an object of the appropriate reference_wrapper type to hold a reference to elem. 其实主要是,如果要向thread传参的时候,该参数在线程内会被修改,需要用这个ref作为一个wrapper将对象包裹成为一个引用然后传入。
("After erase all even numbers, cnt = ", cnt); std::cout << "Erased even numbers: " << erased << '\n'; std::vector<std::complex<double>> nums{{2, 2}, {4, 2}, {4, 8}, {4, 2}}; #ifdef __cpp_lib_algorithm_default_value_type std::erase(nums, {4, 2}); #else ...
std::vector<int> nums = {5,3,4,9,1,7,6,2,8}; std::function<bool(int)> less_than_5 = [](intx){returnx <=5; }; // count numbers of integer that not less and equal than 5 std::cout << std::count_if(nums.begin, nums.end, std::not1(less_than_5)) <<"\n"; ...