public member function
<unordered_set>

std::unordered_set::size

size_type size() const noexcept;
Return container size
Returns the number of elements in the unordered_set container.

Parameters

none

Return Value

The number of elements in the container.

Member type size_type is an unsigned integral type.

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
// unordered_set::size
#include <iostream>
#include <string>
#include <unordered_set>

int main ()
{
  std::unordered_set<std::string> myset;
  std::cout << "0. size: " << myset.size() << std::endl;

  myset = {"milk","potatoes","eggs"};
  std::cout << "1. size: " << myset.size() << std::endl;

  myset.insert ("pineapple");
  std::cout << "2. size: " << myset.size() << std::endl;

  myset.erase ("milk");
  std::cout << "3. size: " << myset.size() << std::endl;

  return 0;
}

Output:
0. size: 0
1. size: 3
2. size: 4
3. size: 3


Complexity

Constant.

Iterator validity

No changes.

See also