unordered_set::unordered_set
Constructs a container object.
unordered_set(
const unordered_set& right);
explicit unordered_set(
size_type nbuckets = N0,
const Hash& hfn = Hash(),
const Pred& comp = Pred(),
const Alloc& al = Alloc());
template<class InIt>
unordered_set(
InIt first, InIt last,
size_type nbuckets = N0,
const Hash& hfn = Hash(),
const Pred& comp = Pred(),
const Alloc& al = Alloc());
unordered_set(
unordered_set&& right);
Parameters
Parameter |
Description |
InIt |
The iterator type. |
al |
The allocator object to store. |
comp |
The comparison function object to store. |
hfn |
The hash function object to store. |
nbuckets |
The minimum number of buckets. |
right |
The container to copy. |
Remarks
The first constructor specifies a copy of the sequence controlled by right. The second constructor specifies an empty controlled sequence. The third constructor inserts the sequence of element values [first, last). The fourth constructor specifies a copy of the sequence by moving right.
All constructors also initialize several stored values. For the copy constructor, the values are obtained from right. Otherwise:
the minimum number of buckets is the argument nbuckets, if present; otherwise it is a default value described here as the implementation-defined value N0.
the hash function object is the argument hfn, if present; otherwise it is Hash().
the comparison function object is the argument comp, if present; otherwise it is Pred().
the allocator object is the argument al, if present; otherwise, it is Alloc().
Example
Code
// std_tr1__unordered_set__unordered_set_construct.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;
Myset c2(8,
std::hash<char>(),
std::equal_to<char>(),
std::allocator<std::pair<const char, int> >());
c2.insert('d');
c2.insert('e');
c2.insert('f');
// display contents " [f] [e] [d]"
for (Myset::const_iterator it = c2.begin();
it != c2.end(); ++it)
std::cout << " [" << *it << "]";
std::cout << std::endl;
Myset c3(c1.begin(),
c1.end(),
8,
std::hash<char>(),
std::equal_to<char>(),
std::allocator<std::pair<const char, int> >());
// display contents " [c] [b] [a]"
for (Myset::const_iterator it = c3.begin();
it != c3.end(); ++it)
std::cout << " [" << *it << "]";
std::cout << std::endl;
Myset c4(std::move(c3));
// display contents " [c] [b] [a]"
for (Myset::const_iterator it = c3.begin();
it != c3.end(); ++it)
std::cout << " [" << *it << "]";
std::cout << std::endl;
return (0);
}
Output
[c] [b] [a]
[f] [e] [d]
[c] [b] [a]
[c] [b] [a]
Requirements
Header: <unordered_set>
Namespace: std