unordered_set::begin
Designates the beginning of the controlled sequence or a bucket.
iterator begin();
const_iterator begin() const;
local_iterator begin(size_type nbucket);
const_local_iterator begin(size_type nbucket) const;
Parameters
Parameter |
Description |
nbucket |
The bucket number. |
Remarks
The first two member functions return a forward iterator that points at the first element of the sequence (or just beyond the end of an empty sequence). The last two member functions return a forward iterator that points at the first element of bucket nbucket (or just beyond the end of an empty bucket).
Example
// unordered_set_begin.cpp
// compile using: cl.exe /EHsc /nologo /W4 /MTd
#include <unordered_set>
#include <iostream>
using namespace std;
typedef unordered_set<char> MySet;
int main()
{
MySet c1;
c1.insert('a');
c1.insert('b');
c1.insert('c');
// display contents using range-based for
for (auto it : c1) {
cout << " [" << it << "]";
}
cout << endl;
// display contents using explicit for
for (MySet::const_iterator it = c1.begin(); it != c1.end(); ++it) {
cout << " [" << *it << "]";
}
cout << std::endl;
// display first two items
MySet::iterator it2 = c1.begin();
cout << " [" << *it2 << "]";
++it2;
cout << " [" << *it2 << "]";
cout << endl;
// display bucket containing 'a'
MySet::const_local_iterator lit = c1.begin(c1.bucket('a'));
cout << " [" << *lit << "]";
return (0);
}
[a] [b] [c] [a] [b] [c] [a] [b] [a]
Requirements
Header: <unordered_set>
Namespace: std