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Set insert - Inserts object x in the set, if x is not already

Set insert - Inserts object x in the set, if x is not already


insert
	
 
Header
<set>

pair<iterator, bool> insert(const value_type& x) 

Inserts object x in the set, if x is not already present in the set. The function returns a pair.

The bool value indicates if the object was inserted in the set.

The iterator indicates the position of the object in the set if the object was inserted in the set; otherwise it indicates the position of the element x already present in the set.

void insert(const value_type* first, const value_type* last)

Inserts the objects specified by the range [first, last) in the set. [first, last) must be a valid range of elements of type value_type.


Sample

#pragma warning(disable: 4786)

#include <set>
#include <iostream>


int main()
{
	//default constructor
	std::set<int> c1 ;

	int ai[] = {0, 1, 2, 3} ;
	
	//construct from a range
	std::set<int> c2(ai, ai + 4) ;

	//copy constructor
	std::set<int> c3(c2) ;

	std::set<int>::iterator Iter ;
	std::set<int>::reverse_iterator RevIter ;

	//empty
	if(c1.empty())
	{
		std::cout << "set c1 is empty" << std::endl ;
	}
	else
	{
		std::cout << "set c1 is not empty" << std::endl ;
	}

	//begin, end
	std::cout << "c2 (using begin, end)  = " ;
	for(Iter = c2.begin(); Iter != c2.end(); Iter++)
	{
		std::cout << *Iter << " " ;
	}
	std::cout << std::endl ;

	//rbegin, rend
	std::cout << "c2 (using rbegin, rend) = " ;
	for(RevIter = c2.rbegin(); RevIter != c2.rend(); RevIter++)
	{
		std::cout << *RevIter << " " ;
	}
	std::cout << std::endl ;

	//insert
	c1.insert(ai, ai+4) ;
	
	std::pair<std::set<int>::iterator, bool> pr ;

	pr = c1.insert(0) ;
	if(pr.second == true)
	{
		std::cout << "element 0 was inserted in c1 successfully" << std::endl ;
	}
	else
	{
		std::cout << "element 0 already exists in c1 and *(pr.first) = " 
			<< *(pr.first) << std::endl ;
	}

	//find
	std::set<int>::const_iterator constIter = c1.find(3) ;
	if(constIter != c1.end())
	{
		std::cout << "c1 contains element 3, *constIter = " 
			<< *constIter << std::endl ;
	}

	//max_size
	std::cout << "c1.max_size() = " << c1.max_size() << std::endl ;

	//size
	std::cout << "c1.size() = " << c1.size() << std::endl ;

	//swap
	c1.insert(4) ;
	c2.swap(c1) ;
	std::cout << "The last element of c2 = " << *(c2.rbegin())
		<< std::endl ;

	//clear
	c1.clear() ;
	std::cout << "After calling c1.clear(), c1.size() = " 
		<< c1.size() << std::endl ;

	//get_allocator
	std::set<int>::allocator_type a1 = c1.get_allocator() ;

	//key_compare
	std::set<int>::key_compare kc = c2.key_comp() ;
	bool result = kc(2, 3) ;
	if(result == true)
	{
		std::cout << "kc is function object used by c2.  kc(2,3) = true" << std::endl ;
	}
	else
	{
		std::cout << "kc is function object used by c2.  kc(2,3) = false" << std::endl ;
	}

	//value_comp
	std::set<int>::value_compare vc = c2.value_comp() ;
	result = vc(10, 4) ;
	if(result == true)
	{
		std::cout << "vc is function object used by c2.  vc(10,4) = true" << std::endl ;
	}
	else
	{
		std::cout << "vc is function object used by c2.  vc(10,4) = false" << std::endl ;
	}

	//upper_bound
	std::cout << "* (c2.upper_bound(3)) = " 
		<< *(c2.upper_bound(3)) << std::endl ;

	//lower_bound
	std::cout << "* (c2.lower_bound(3)) = " 
		<< *(c2.lower_bound(3)) << std::endl ;

	//equal_range
	std::pair<std::set<int>::const_iterator, std::set<int>::const_iterator> pr1 = c2.equal_range(3) ;
	std::cout << "*(pr1.first) = " << *(pr1.first) << "\t" 
		<< "*(pr1.second) = " << *(pr1.second) << std::endl ;

	//erase
	if(c3.erase(1) != 0)
	{
		std::cout << "c3 does not contain 1 any more" << std::endl ;
	}
	else
	{
		std::cout << "No elements in c3 match key 1" << std::endl ;
	}

	if((c2.erase(c2.begin())) != c2.end())
	{
		std::cout << "c2 does not contain 0 any more" << std::endl ;
	}
	else
	{
		std::cout << "No elements in c2 match key 0" << std::endl ;
	}

	c3.erase(c3.begin(), c3.end()) ;
	std::cout << "after c3.erase(c3.begin(), c3.end()), c3.size() = " 
		<< c3.size() << std::endl ;
	

	return 0 ;
}

Program Output

set c1 is empty
c2 (using begin, end)  = 0 1 2 3
c2 (using rbegin, rend) = 3 2 1 0
element 0 already exists in c1 and *(pr.first) = 0
c1 contains element 3, *constIter = 3
c1.max_size() = 1073741823
c1.size() = 4
The last element of c2 = 4
After calling c1.clear(), c1.size() = 0
kc is function object used by c2.  kc(2,3) = true
vc is function object used by c2.  vc(10,4) = false
* (c2.upper_bound(3)) = 4
* (c2.lower_bound(3)) = 3
*(pr1.first) = 3        *(pr1.second) = 4
c3 does not contain 1 any more
c2 does not contain 0 any more
after c3.erase(c3.begin(), c3.end()), c3.size() = 0