std::unordered_set::empty
来自cppreference.com
< cpp | container | unordered set
 |
This page has been machine-translated from the English version of the wiki using Google Translate.
The translation may contain errors and awkward wording. Hover over text to see the original version. You can help to fix errors and improve the translation. For instructions click here. |
| bool empty() const; |
（C++11 起） | |
检查，如果容器有任何元素，即是否begin() == end().
Original:
Checks if the container has no elements, i.e. whether begin() == end().
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
目录 |
[编辑] 参数
（无）
Original:
(none)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
[编辑] 返回值
true如果容器是空的，false其他方式
Original:
true if the container is empty, false otherwise
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
[编辑] 例外
[编辑] 复杂性
常数
Original:
Constant
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
[编辑] 为例
下面的代码使用
empty检查，如果std::unordered_set<int>包含任何元素
Original:
The following code uses
empty to check if a std::unordered_set<int> contains any elements:
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
#include <unordered_set> #include <iostream> int main() { std::unordered_set<int> numbers; std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n'; numbers.push_back(42); numbers.push_back(13317); std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n'; }
Output:
Initially, numbers.empty(): 1 After adding elements, numbers.empty(): 0
See also
| 返回的元素数 Original: returns the number of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （公共成员函数） | |
