在线文档教程
首页 技术教程 开发文档 觅分类 ICON图标
技术教程 开发文档 觅分类 ICON图标
Bootstrap 4
Bootstrap 3
C
C++
算法 | Algorithm
原子性操作 | Atomic operations
概念 | Concepts
容器 | Containers
cbefore_begin
Containers library
Node handle
operators (std::array)
operators (std::deque)
operators (std::forward_list)
operators (std::list)
operators (std::map)
operators (std::multimap)
operators (std::multiset)
operators (std::queue)
operators (std::set)
operators (std::stack)
operators (std::unordered_map)
operators (std::unordered_multimap)
operators (std::unordered_multiset)
operators (std::unordered_set)
operators (std::vector)
remove_if
remove_if
std::array
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
std::array::rend
std::array::size
std::array::swap
std::deque
std::deque::assign
std::deque::at
std::deque::back
std::deque::begin
std::deque::cbegin
std::deque::cend
std::deque::clear
std::deque::crbegin
std::deque::crend
std::deque::deque
std::deque::emplace
std::deque::emplace_back
std::deque::emplace_front
std::deque::empty
std::deque::end
std::deque::erase
std::deque::front
std::deque::get_allocator
std::deque::insert
std::deque::max_size
std::deque::operator[]
std::deque::pop_back
std::deque::pop_front
std::deque::push_back
std::deque::push_front
std::deque::rbegin
std::deque::rend
std::deque::resize
std::deque::shrink_to_fit
std::deque::size
std::deque::swap
std::forward_list
std::forward_list::assign
std::forward_list::before_begin
std::forward_list::begin
std::forward_list::cbegin
std::forward_list::cend
std::forward_list::clear
std::forward_list::emplace_after
std::forward_list::emplace_front
std::forward_list::empty
std::forward_list::end
std::forward_list::erase_after
std::forward_list::forward_list
std::forward_list::front
std::forward_list::get_allocator
std::forward_list::insert_after
std::forward_list::max_size
std::forward_list::merge
std::forward_list::pop_front
std::forward_list::push_front
std::forward_list::remove
std::forward_list::resize
std::forward_list::reverse
std::forward_list::sort
std::forward_list::splice_after
std::forward_list::swap
std::forward_list::unique
std::get(std::array)
std::hash
std::list
std::list::assign
std::list::back
std::list::begin
std::list::cbegin
std::list::cend
std::list::clear
std::list::crbegin
std::list::crend
std::list::emplace
std::list::emplace_back
std::list::emplace_front
std::list::empty
std::list::end
std::list::erase
std::list::front
std::list::get_allocator
std::list::insert
std::list::list
std::list::max_size
std::list::merge
std::list::pop_back
std::list::pop_front
std::list::push_back
std::list::push_front
std::list::rbegin
std::list::remove
std::list::rend
std::list::resize
std::list::reverse
std::list::size
std::list::sort
std::list::splice
std::list::swap
std::list::unique
std::map
std::map::at
std::map::begin
std::map::cbegin
std::map::cend
std::map::clear
std::map::count
std::map::crbegin
std::map::crend
std::map::emplace
std::map::emplace_hint
std::map::empty
std::map::end
std::map::equal_range
std::map::erase
std::map::extract
std::map::find
std::map::get_allocator
std::map::insert
std::map::insert_or_assign
std::map::key_comp
std::map::lower_bound
std::map::map
std::map::max_size
std::map::merge
std::map::operator[]
std::map::rbegin
std::map::rend
std::map::size
std::map::swap
std::map::try_emplace
std::map::upper_bound
std::map::value_comp
std::map::value_compare
std::multimap
std::multimap::begin
std::multimap::cbegin
std::multimap::cend
std::multimap::clear
std::multimap::count
std::multimap::crbegin
std::multimap::crend
std::multimap::emplace
std::multimap::emplace_hint
std::multimap::end
std::multimap::equal_range
std::multimap::erase
std::multimap::extract
std::multimap::find
std::multimap::get_allocator
std::multimap::insert
std::multimap::key_comp
std::multimap::lower_bound
std::multimap::max_size
std::multimap::merge
std::multimap::multimap
std::multimap::rbegin
std::multimap::rend
std::multimap::size
std::multimap::swap
std::multimap::upper_bound
std::multimap::value_comp
std::multimap::value_compare
std::multiset
std::multiset::begin
std::multiset::cbegin
std::multiset::cend
std::multiset::clear
std::multiset::count
std::multiset::crbegin
std::multiset::crend
std::multiset::emplace
std::multiset::emplace_hint
std::multiset::empty
std::multiset::end
std::multiset::equal_range
std::multiset::erase
std::multiset::extract
std::multiset::find
std::multiset::get_allocator
std::multiset::insert
std::multiset::key_comp
std::multiset::lower_bound
std::multiset::max_size
std::multiset::merge
std::multiset::multiset
std::multiset::rbegin
std::multiset::rend
std::multiset::size
std::multiset::swap
std::multiset::upper_bound
std::multiset::value_comp
std::priority_queue
std::priority_queue::emplace
std::priority_queue::empty
std::priority_queue::pop
std::priority_queue::priority_queue
std::priority_queue::push
std::priority_queue::size
std::priority_queue::swap
std::priority_queue::top
std::queue
std::queue::back
std::queue::emplace
std::queue::empty
std::queue::front
std::queue::pop
std::queue::push
std::queue::queue
std::queue::size
std::queue::swap
std::set
std::set::begin
std::set::cbegin
std::set::cend
std::set::clear
std::set::count
std::set::crbegin
std::set::crend
std::set::emplace
std::set::emplace_hint
std::set::empty
std::set::end
std::set::equal_range
std::set::erase
std::set::extract
std::set::find
std::set::get_allocator
std::set::insert
std::set::key_comp
std::set::lower_bound
std::set::max_size
std::set::merge
std::set::rbegin
std::set::rend
std::set::set
std::set::size
std::set::swap
std::set::upper_bound
std::set::value_comp
std::stack
std::stack::emplace
std::stack::empty
std::stack::pop
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::priority_queue)
std::swap(std::queue)
std::swap(std::set)
std::swap(std::stack)
std::swap(std::unordered_map)
std::swap(std::unordered_multimap)
std::swap(std::unordered_multiset)
std::swap(std::unordered_set)
std::swap(std::vector)
std::tuple_element<std::array>
std::tuple_size(std::array)
std::unordered_map
std::unordered_map::at
std::unordered_map::begin
std::unordered_map::begin(int)
std::unordered_map::bucket
std::unordered_map::bucket_count
std::unordered_map::bucket_size
std::unordered_map::cbegin
std::unordered_map::cbegin
std::unordered_map::cend
std::unordered_map::cend
std::unordered_map::clear
std::unordered_map::count
std::unordered_map::emplace
std::unordered_map::emplace_hint
std::unordered_map::empty
std::unordered_map::end
std::unordered_map::end(int)
std::unordered_map::equal_range
std::unordered_map::erase
std::unordered_map::extract
std::unordered_map::find
std::unordered_map::get_allocator
std::unordered_map::hash_function
std::unordered_map::insert
std::unordered_map::insert_or_assign
std::unordered_map::key_eq
std::unordered_map::load_factor
std::unordered_map::max_bucket_count
std::unordered_map::max_load_factor
std::unordered_map::max_size
std::unordered_map::merge
std::unordered_map::operator[]
std::unordered_map::rehash
std::unordered_map::reserve
std::unordered_map::size
std::unordered_map::swap
std::unordered_map::try_emplace
std::unordered_map::unordered_map
std::unordered_multimap
std::unordered_multimap::begin
std::unordered_multimap::begin(int)
std::unordered_multimap::bucket
std::unordered_multimap::bucket_count
std::unordered_multimap::bucket_size
std::unordered_multimap::cbegin
std::unordered_multimap::cbegin
std::unordered_multimap::cend
std::unordered_multimap::cend
std::unordered_multimap::clear
std::unordered_multimap::count
std::unordered_multimap::emplace
std::unordered_multimap::emplace_hint
std::unordered_multimap::empty
std::unordered_multimap::end
std::unordered_multimap::end(int)
std::unordered_multimap::equal_range
std::unordered_multimap::erase
std::unordered_multimap::extract
std::unordered_multimap::find
std::unordered_multimap::get_allocator
std::unordered_multimap::hash_function
std::unordered_multimap::insert
std::unordered_multimap::key_eq
std::unordered_multimap::load_factor
std::unordered_multimap::max_bucket_count
std::unordered_multimap::max_load_factor
std::unordered_multimap::max_size
std::unordered_multimap::merge
std::unordered_multimap::rehash
std::unordered_multimap::reserve
std::unordered_multimap::size
std::unordered_multimap::swap
std::unordered_multimap::unordered_multimap
std::unordered_multiset
std::unordered_multiset::begin
std::unordered_multiset::begin(int)
std::unordered_multiset::bucket
std::unordered_multiset::bucket_count
std::unordered_multiset::bucket_size
std::unordered_multiset::cbegin
std::unordered_multiset::cbegin
std::unordered_multiset::cend
std::unordered_multiset::cend
std::unordered_multiset::clear
std::unordered_multiset::count
std::unordered_multiset::emplace
std::unordered_multiset::emplace_hint
std::unordered_multiset::empty
std::unordered_multiset::end
std::unordered_multiset::end(int)
std::unordered_multiset::equal_range
std::unordered_multiset::erase
std::unordered_multiset::extract
std::unordered_multiset::find
std::unordered_multiset::get_allocator
std::unordered_multiset::hash_function
std::unordered_multiset::insert
std::unordered_multiset::key_eq
std::unordered_multiset::load_factor
std::unordered_multiset::max_bucket_count
std::unordered_multiset::max_load_factor
std::unordered_multiset::max_size
std::unordered_multiset::merge
std::unordered_multiset::rehash
std::unordered_multiset::reserve
std::unordered_multiset::size
std::unordered_multiset::swap
std::unordered_multiset::unordered_multiset
std::unordered_set
std::unordered_set::begin
std::unordered_set::begin(int)
std::unordered_set::bucket
std::unordered_set::bucket_count
std::unordered_set::bucket_size
std::unordered_set::cbegin
std::unordered_set::cbegin
std::unordered_set::cend
std::unordered_set::cend
std::unordered_set::clear
std::unordered_set::count
std::unordered_set::emplace
std::unordered_set::emplace_hint
std::unordered_set::empty
std::unordered_set::end
std::unordered_set::end(int)
std::unordered_set::equal_range
std::unordered_set::erase
std::unordered_set::extract
std::unordered_set::find
std::unordered_set::get_allocator
std::unordered_set::hash_function
std::unordered_set::insert
std::unordered_set::key_eq
std::unordered_set::load_factor
std::unordered_set::max_bucket_count
std::unordered_set::max_load_factor
std::unordered_set::max_size
std::unordered_set::merge
std::unordered_set::rehash
std::unordered_set::reserve
std::unordered_set::size
std::unordered_set::swap
std::unordered_set::unordered_set
std::uses_allocator<std::priority_queue>
std::uses_allocator<std::queue>
std::uses_allocator<std::stack>
std::vector
std::vector::assign
std::vector::at
std::vector::back
std::vector::begin
std::vector::capacity
std::vector::cbegin
std::vector::cend
std::vector::clear
std::vector::crbegin
std::vector::crend
std::vector::data
std::vector::emplace
std::vector::emplace_back
std::vector::empty
std::vector::end
std::vector::erase
std::vector::front
std::vector::get_allocator
std::vector::insert
std::vector::max_size
std::vector::operator[]
std::vector::pop_back
std::vector::push_back
std::vector::rbegin
std::vector::rend
std::vector::reserve
std::vector::resize
std::vector::shrink_to_fit
std::vector::size
std::vector::swap
std::vector::vector
std::vector<bool>
std::vector<bool>::flip
std::vector<bool>::reference
std::vector<bool>::swap
动态内存管理 | Dynamic memory management
文件系统 | Filesystem
输入/输出 | Input/output
迭代器 | Iterator
关键词 | Keywords
语言 | Language
本土化 | Localizations
数字 | Numerics
规律表达 | Regular expressions
标准库头文件 | Standard library header files
字符串 | Strings
线程支持 | Thread support
应用 | Utilities
Clojure 1.8
Codeigniter 3
CSS
Docker 17
Electron
Elixir 1.5
Erlang 20
Eslint
Express
Git
Go
HTML
HTTP
Immutable 3.8.1
JavaScript
Lodash 4
Lua 5.3
Nginx
PHP
Phpunit 6
Python
React
React native
Redis
Redux
Ruby 2.4
Sass
Scikit image
Socket.IO
Sqlite
SVG
TensorFlow Guide
Typescript
Underscore
Vue 2
Webpack
Xslt & Xpath
Yarn
RxJS 5
Rollup.js
Babel
Parcel
MobX
Koa
Angular
Gulp
Grunt
Stylelint
Standard JS
Element UI
iView UI
Lavas
Mint UI
PostCSS
ThinkJS
Nest
npm
Node.js教程
JSON教程
Groovy教程
vb.net教程
Storm入门教程
Hibernate 教程
Slick教程
MongoDB教程
Yii 2.0

std::multimap::empty

STD：：Multimap：：空

bool empty() const;​​

检查容器是否没有元素，即是否begin() == end()...

参数

%280%29

返回值

true如果容器是空的，false否则。

例外

(none)(until C++11)
noexcept specification: noexcept(since C++11)

复杂性

常量。

例

下面的代码使用empty以检查std::multimap<int, int>包含任何元素：

二次

#include <map>
#include <iostream>
#include <utility>
 
int main()
{
    std::multimap<int, int> numbers;
    std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n';
 
    numbers.emplace(42, 13
    numbers.insert(std::make_pair(13317, 123)  
    std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n';
}

二次

产出：

二次

Initially, numbers.empty(): 1
After adding elements, numbers.empty(): 0

二次

另见

sizereturns the number of elements (public member function)

 © cppreference.com

在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。

http：//en.cppreference.com/w/cpp/容器/Multimap/空

  • 黔ICP备2021005045号