set::insert
Inserts an element or a range of elements into a set.
pair <iterator, bool> insert(
const value_type& _Val
);
iterator insert(
iterator _Where,
const value_type& _Val
);
template<class InputIterator>
void insert(
InputIterator _First,
InputIterator _Last
);
Parameters
_Val
The value of an element to be inserted into the set unless the set already contains that element or, more generally, an element whose key is equivalently ordered._Where
The place to start searching for the correct point of insertion. (Insertion can occur in amortized constant time, instead of logarithmic time, if the insertion point immediately follows _Where.)_First
The position of the first element to be copied from a set._Last
The position just beyond the last element to be copied from a set.
Return Value
The first insert member function returns a pair whose bool component returns true if an insertion was make and false if the set already contained an element whose key had an equivalent value in the ordering, and whose iterator component returns the address where a new element was inserted or where the element was already located.
To access the iterator component of a pair pr returned by this member function, use pr.first, and to dereference it, use *(pr.first). To access the bool component of a pair pr returned by this member function, use pr.second.
The second insert member function returns an iterator that points to the position where the new element was inserted into the set.
Remarks
The third member function inserts the sequence of element values into a set corresponding to each element addressed by an iterator of in the range [_First, _Last) of a specified set.
Example
// set_insert.cpp
// compile with: /EHsc
#include <set>
#include <iostream>
int main( )
{
using namespace std;
set <int>::iterator s1_pIter, s2_pIter;
set <int, less<int> > s1, s2;
s1.insert( 10 );
s1.insert( 20 );
s1.insert( 30 );
s1.insert( 40 );
cout << "The original s1 =";
for ( s1_pIter = s1.begin( ); s1_pIter != s1.end( ); s1_pIter++ )
cout << " " << *s1_pIter;
cout << "." << endl;
pair< set<int>::iterator, bool > pr;
pr = s1.insert( 10 );
if(pr.second == true)
{
cout << "The element 10 was inserted in s1 successfully."
<< endl;
}
else
{
cout << "The element 10 already exists in s1 and"
<< " *( pr.first ) = " << *( pr.first ) << "." << endl;
}
s1.insert( --s1.end( ), 50 );
cout << "After the insertions, s1 =";
for ( s1_pIter = s1.begin( ); s1_pIter != s1.end( ); s1_pIter++ )
cout << " " << *s1_pIter;
cout << "." << endl;
s2.insert( 100 );
s2.insert( ++s1.begin( ), --s1.end( ) );
cout << "s2 =";
for ( s2_pIter = s2.begin( ); s2_pIter != s2.end( ); s2_pIter++ )
cout << " " << *s2_pIter;
cout << "." << endl;
}
The original s1 = 10 20 30 40.
The element 10 already exists in s1 and *( pr.first ) = 10.
After the insertions, s1 = 10 20 30 40 50.
s2 = 20 30 40 100.
Requirements
Header: <set>
Namespace: std