insert |
C++ Library |
pair<iterator, bool> insert(const value_type& x)
Inserts object x in the map, if x is not already present in the map. The function returns a pair.
The bool value indicates if the object was inserted in the map.
If the object was inserted in the map, the iterator indicates the position of
the object in the map; otherwise, the iterator indicates the position of element x
already present in the map.
void insert(const value_type* first, const value_type* last)
Inserts the objects specified by the range [first, last) in the map. [first, last) must be a valid range of elements of type value_type.
void insert(iterator pos, const value_type& x)
If the object was inserted in the map, the iterator indicates the position of the object in the map; otherwise, the iterator indicates the position of element x already present in the map.
#pragma warning(disable: 4786)
#include <map>
#include <iostream>
#include <string>
typedef std::map<int, std::string> MAP_INT_STR ;
typedef MAP_INT_STR::iterator MAP_ITERATOR ;
typedef MAP_INT_STR::reverse_iterator MAP_REVERSE_ITERATOR ;
typedef std::pair<int, std::string> PAIR_INT_STR ;
template <class ITERATOR>
void print_map_item(ITERATOR it)
{
std::cout << (*it).first << ", " <<
(*it).second << std::endl ;
}
int main()
{
//default constructor
MAP_INT_STR c1 ;
PAIR_INT_STR pairs[5] = { PAIR_INT_STR(1, std::string("one")),
PAIR_INT_STR(2, std::string("two")),
PAIR_INT_STR(3, std::string("three")),
PAIR_INT_STR(4, std::string("four")),
PAIR_INT_STR(5, std::string("five"))
};
//construct from a range
MAP_INT_STR c2(pairs, pairs + 5) ;
//copy constructor
MAP_INT_STR c3(c2) ;
//empty
if(c1.empty())
{
std::cout << "c1 is empty" << std::endl ;
}
else
{
std::cout << "c1 is not empty" << std::endl ;
}
//begin, end
std::cout << "c2 (using begin, end) = " << std::endl ;
MAP_ITERATOR Iter1 ;
for(Iter1 = c2.begin(); Iter1 != c2.end(); Iter1++)
{
print_map_item(Iter1) ;
}
//rbegin, rend
std::cout << "c2 (using rbegin, rend) = " << std::endl ;
MAP_REVERSE_ITERATOR RevIter1 ;
for(RevIter1 = c2.rbegin(); RevIter1 != c2.rend(); RevIter1++)
{
print_map_item(RevIter1) ;
}
//insert
std::pair<MAP_ITERATOR, bool> result ;
result = c1.insert(MAP_INT_STR::value_type(6, std::string("six"))) ;
if(result.second == true)
{
std::cout << "a pair of key/data was inserted in c1, *(result.first) = " ;
print_map_item(result.first);
}
else
{
std::cout << "pair(6, \"six\") was not inserted in c1" << std::endl ;
}
c1.insert(pairs, pairs + 5) ;
c1.insert(c1.begin(), PAIR_INT_STR(0, std::string("zero"))) ;
//find
std::cout << "Does c1 contain any pair with key = 6?" << std::endl ;
Iter1 = c1.find(6) ;
if(Iter1 != c1.end())
{
std::cout << "c1 contains pair:" ;
print_map_item(Iter1) ;
}
else
{
std::cout << "c1 does not contain any element with key = 6" << std::endl ;
}
//operator[]
c1[8] = "eight" ;
std::cout << "Last key/data pair in c1 = " ;
print_map_item(c1.rbegin()) ;
//max_size
std::cout << "max elements which c1 can hold uisng current allocator = "
<< c1.max_size() << std::endl ;
//size
std::cout << "number of elements in c1 = " << c1.size() << std::endl ;
//swap
c1.swap(c2) ;
std::cout << "Last key/data pair in c1 = " ;
print_map_item(c1.rbegin()) ;
//clear
c3.clear() ;
std::cout << "after calling c3.clear(), number of elements in c3 = "
<< c3.size() << std::endl ;
//get_allocator
MAP_INT_STR::allocator_type a1 = c3.get_allocator() ;
//key_comp
MAP_INT_STR::key_compare kc = c1.key_comp() ;
std::cout << "use function object kc to find less of (10, 4)..."
<< std::endl ;
if (kc(10, 4) == true)
std::cout << "kc(10, 4) == true, which means 10 < 4" << std::endl ;
else
std::cout << "kc(10, 4) == false, which means 10 > 4" << std::endl ;
//value_comp
MAP_INT_STR::value_compare vc = c1.value_comp() ;
std::cout << "use function object vc to compare int-string pairs..."
<< std::endl ;
std::cout << "pairs[0] = (" << pairs[0].first << ", "
<< pairs[0].second << ")" << std::endl ;
std::cout << "pairs[1] = (" << pairs[1].first << ", "
<< pairs[1].second << ")" << std::endl ;
if ( vc(pairs[0], pairs[1]) == true)
std::cout << "pairs[0] < pairs[1]" << std::endl ;
else
std::cout << "pairs[0] > pairs[1]" << std::endl ;
//upper_bound
Iter1 = c2.upper_bound(6) ;
std::cout << "first map element with key > 6 = " ;
print_map_item(Iter1) ;
//lower_bound
Iter1 = c2.lower_bound(6) ;
std::cout << "first map element with key 6 = " ;
print_map_item(Iter1) ;
//equal_range
std::pair<MAP_ITERATOR, MAP_ITERATOR> pair2 = c2.equal_range(6) ;
std::cout << "using c2.equal_range(6),first map element with key > 6 = " ;
print_map_item(pair2.second) ;
std::cout << "using c2.equal_range(6), first map element with key = 6 = " ;
print_map_item(pair2.first) ;
//count
std::cout << "does c2 contain an element with key 8 ?" << std::endl ;
if(c2.count(8) == 1)
{
std::cout << "c2 contains element with key 8" << std::endl ;
}
else
{
std::cout << "c2 does not contain element with key 8" << std::endl ;
}
//erase
c2.erase(c2.begin()) ;
std::cout << "first key/data pair of c2 is: " ;
print_map_item(c2.begin()) ;
c1.erase(c1.begin(), c1.end()) ;
std::cout << "after c1.erase(c1.begin(), c2.end()), number of elements in c1 = "
<< c1.size() << std::endl ;
if(c2.erase(8) == 1)
{
std::cout << "element with key 8 in c2 was erased" << std::endl ;
}
else
{
std::cout << "c2 does not contain any element with key 8" << std::endl ;
}
return 0 ;
}
c1 is empty c2 (using begin, end) = 1, one 2, two 3, three 4, four 5, five c2 (using rbegin, rend) = 5, five 4, four 3, three 2, two 1, one a pair of key/data was inserted in c1, *(result.first) = 6, six Does c1 contain any pair with key = 6? c1 contains pair:6, six Last key/data pair in c1 = 8, eight max elements which c1 can hold uisng current allocator = 268435455 number of elements in c1 = 8 Last key/data pair in c1 = 5, five after calling c3.clear(), number of elements in c3 = 0 use function object kc to find less of (10, 4)... kc(10, 4) == false, which means 10 > 4 use function object vc to compare int-string pairs... pairs[0] = (1, one) pairs[1] = (2, two) pairs[0] < pairs[1] first map element with key > 6 = 8, eight first map element with key 6 = 6, six using c2.equal_range(6),first map element with key > 6 = 8, eight using c2.equal_range(6), first map element with key = 6 = 6, six does c2 contain an element with key 8 ? c2 contains element with key 8 first key/data pair of c2 is: 1, one after c1.erase(c1.begin(), c2.end()), number of elements in c1 = 0 element with key 8 in c2 was erased