unordered_set::size
Counts the number of elements.
size_type size() const;
Remarks
The member function returns the length of the controlled sequence.
Example
// std_tr1__unordered_set__unordered_set_size.cpp
// compile with: /EHsc
#include <unordered_set>
#include <iostream>
typedef std::unordered_set<char> Myset;
int main()
{
Myset c1;
c1.insert('a');
c1.insert('b');
c1.insert('c');
// display contents " [c] [b] [a]"
for (Myset::const_iterator it = c1.begin();
it != c1.end(); ++it)
std::cout << " [" << *it << "]";
std::cout << std::endl;
// clear the container and reinspect
c1.clear();
std::cout << "size == " << c1.size() << std::endl;
std::cout << "empty() == " << std::boolalpha << c1.empty() << std::endl;
std::cout << std::endl;
c1.insert('d');
c1.insert('e');
// display contents " [e] [d]"
for (Myset::const_iterator it = c1.begin();
it != c1.end(); ++it)
std::cout << " [" << *it << "]";
std::cout << std::endl;
std::cout << "size == " << c1.size() << std::endl;
std::cout << "empty() == " << std::boolalpha << c1.empty() << std::endl;
return (0);
}
[c] [b] [a] size == 0 empty() == true [e] [d] size == 2 empty() == false
Requirements
Header: <unordered_set>
Namespace: std