c++ Muitmaps
Muitmaps 是存储由密钥值和映射值的组合构成的元素，下列特定的顺序关联容器，以及其中多个元件可具有等价密钥。 在一个multimap中，关键值一般用于排序和唯一标识的元素，而映射的值存储关联于该键的内容。类型的键和映射值可能不同，并且在构件的类型的value_type，这是一对型组合都被分组在一起： ms-help://MS.MSDNQTR.v90.chs/dv_vcstdlib/html/0e9125b6-620c-4f68-9f91-3b5d6ca509d0.htm http://www.cplusplus.com/reference/map/multimap/?kw=multimap begin 返回迭代开始 end 返回迭代结束 rbegin 返回反向迭代器反向开始 rend 返回反向迭代器反向端 cbegin 返回的const_iterator开头 cend 返回的const_iterator结束 crbegin 返回的const_reverse_iterator反转开始 crend 返回的const_reverse_iterator反向端 empty 测试容器是否是空的 size 返回容器的大小 max_size返回最大尺寸 insert 插入元素 erase 删除元素 swap 交换的内容 clear 清除内容 emplace 构建并插入元素 emplace_hint 构建并插入提示元素 key_comp返回键比较对象 value_comp返回值比较对象 find 获得迭代器元素 count 算上与特定的要素 lower_bound 返回迭代器下限 upper_bound 返回迭代上限 equal_range 获得平等的要素的范围 get_allocator 获得分配
<pre name="code" class="cpp">#include <map>
#include <iostream>
#include <xfunctional>
//构造函数
void multimapConstructor(void);
//返回一个迭代解决multimap中的第一个元素
void multimap_begin(void);
//擦除一个multimap中的所有元素
void multimap_clear(void);
//返回multimap中的，其关键的参数 - 指定键匹配元件的数目
void multimap_count(void);
//返回multimap是否为空
void mulitmap_empty(void);
//返回地址multimap中取得成功的最后一个元素的位置的迭代器
void mulitmap_end(void);
//发现的元素，其中的元素的键相匹配的指定值的范围内
void mulitmap_equal_range(void);
//删除元素或一个范围内指定位置multimap中的元素或删除匹配指定键的元素
void muiltmap_erase(void);
//返回迭代寻址在具有关键相当于一个指定键的multimap中一个元件的第一位置
void muiltmap_find(void);
//返回用于构造multimap中的分配对象的副本
void muiltmap_get_allocator(void);
//插入一个元素或一定范围内的元素到multimap中的
void muiltmap_insert(void);
//检索用于multimap中的命令的键的比较对象的副本
void muiltmap_key_comp(void);
//返回一个迭代到第一元件multimap中的，与一个键比指定的键等于或大于
void muiltmap_lower_bound(void);
//返回multimap中的最大长度
void muiltmap_max_size(void);
//返回一个迭代解决的第一个元素在逆转多重映射
void muiltmap_rbegin(void);
//返回解决了一个逆转多重映射成功的最后一个元素的位置的迭代器
void muiltmap_rend(void);
//返回multimap中元素的数量
void muiltmap_size(void);
//交换两个muiltmap的元素
void muiltmap_swap(void);
//返回一个迭代器的第一个元素multimap中以关键比指定的键更大
void muiltmap_upper_bound(void);
//成员函数返回一个功能对象，通过比较它们的键值确定multimap中的元素的顺序
void muiltmap_value_comp(void);
int main()
{
//multimapConstructor();
//multimap_begin();
//multimap_clear();
//multimap_count();
//mulitmap_empty();
//mulitmap_end();
//mulitmap_equal_range();
//muiltmap_erase();
//muiltmap_find();
//muiltmap_get_allocator();
//muiltmap_insert();
//muiltmap_key_comp();
//muiltmap_lower_bound();
//muiltmap_max_size();
//muiltmap_rbegin();
//muiltmap_rend();
//muiltmap_size();
//muiltmap_swap();
//muiltmap_upper_bound();
muiltmap_value_comp();
return 0;
}
//构造函数
void multimapConstructor(void)
{
using namespace std;
typedef pair <int, int> Int_Pair;
multimap <int, int>::iterator m1_Iter, m3_Iter, m4_Iter, m5_Iter, m6_Iter;
multimap <int, int, greater<int> >::iterator m2_Iter;
// Create an empty multimap m0 of key type integer
multimap <int, int> m0;
// Create an empty multimap m1 with the key comparison
// function of less than, then insert 4 elements
multimap <int, int, less<int> > m1;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
m1.insert(Int_Pair(4, 40));
// Create an empty multimap m2 with the key comparison
// function of geater than, then insert 2 elements
multimap <int, int, greater<int> > m2;
m2.insert(Int_Pair(1, 10));
m2.insert(Int_Pair(2, 20));
// Create a multimap m3 with the
// allocator of multimap m1
multimap <int, int>::allocator_type m1_Alloc;
m1_Alloc = m1.get_allocator();
multimap <int, int> m3(less<int>(), m1_Alloc);
m3.insert(Int_Pair(3, 30));
// Create a copy, multimap m4, of multimap m1
multimap <int, int> m4(m1);
// Create a multimap m5 by copying the range m1[_First, _Last)
multimap <int, int>::const_iterator m1_bcIter, m1_ecIter;
m1_bcIter = m1.begin();
m1_ecIter = m1.begin();
m1_ecIter++;
m1_ecIter++;
multimap <int, int> m5(m1_bcIter, m1_ecIter);
// Create a multimap m6 by copying the range m4[_First, _Last)
// and with the allocator of multimap m2
multimap <int, int>::allocator_type m2_Alloc;
m2_Alloc = m2.get_allocator();
multimap <int, int> m6(m4.begin(), ++m4.begin(), less<int>(), m2_Alloc);
cout << "m1 =";
for (m1_Iter = m1.begin(); m1_Iter != m1.end(); m1_Iter++)
cout << " " << m1_Iter->second;
cout << endl;
cout << "m2 =";
for (m2_Iter = m2.begin(); m2_Iter != m2.end(); m2_Iter++)
cout << " " << m2_Iter->second;
cout << endl;
cout << "m3 =";
for (m3_Iter = m3.begin(); m3_Iter != m3.end(); m3_Iter++)
cout << " " << m3_Iter->second;
cout << endl;
cout << "m4 =";
for (m4_Iter = m4.begin(); m4_Iter != m4.end(); m4_Iter++)
cout << " " << m4_Iter->second;
cout << endl;
cout << "m5 =";
for (m5_Iter = m5.begin(); m5_Iter != m5.end(); m5_Iter++)
cout << " " << m5_Iter->second;
cout << endl;
cout << "m6 =";
for (m6_Iter = m6.begin(); m6_Iter != m6.end(); m6_Iter++)
cout << " " << m6_Iter->second;
cout << endl;
return;
/*
m1 = 10 20 30 40
m2 = 20 10
m3 = 30
m4 = 10 20 30 40
m5 = 10 20
m6 = 10
请按任意键继续. . .
*/
}
//返回一个迭代解决multimap中的第一个元素
void multimap_begin()
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::iterator m1_Iter;
multimap <int, int> ::const_iterator m1_cIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(0, 0));
m1.insert(Int_Pair(1, 1));
m1.insert(Int_Pair(2, 4));
m1_cIter = m1.begin();
cout << "The first element of m1 is " << m1_cIter->first << endl;
m1_Iter = m1.begin();
m1.erase(m1_Iter);
// The following 2 lines would err as the iterator is const
// m1_cIter = m1.begin ( );
// m1.erase ( m1_cIter );
m1_cIter = m1.begin();
cout << "First element of m1 is now " << m1_cIter->first << endl;
return;
/*
The first element of m1 is 0
First element of m1 is now 1
请按任意键继续. . .
*/
}
//擦除一个multimap中的所有元素
void multimap_clear(void)
{
using namespace std;
multimap<int, int> m1;
multimap<int, int>::size_type i;
typedef pair<int, int> Int_Pair;
m1.insert(Int_Pair(1, 1));
m1.insert(Int_Pair(2, 4));
i = m1.size();
cout << "The size of the multimap is initially "
<< i << "." << endl;
m1.clear();
i = m1.size();
cout << "The size of the multimap after clearing is "
<< i << "." << endl;
return;
/*
The size of the multimap is initially 2.
The size of the multimap after clearing is 0.
请按任意键继续. . .
*/
}
//返回multimap中的，其关键的参数 - 指定键匹配元件的数目
void multimap_count(void)
{
using namespace std;
multimap<int, int> m1;
multimap<int, int>::size_type i;
typedef pair<int, int> Int_Pair;
m1.insert(Int_Pair(1, 1));
m1.insert(Int_Pair(2, 1));
m1.insert(Int_Pair(1, 4));
m1.insert(Int_Pair(2, 1));
// Elements do not need to have unique keys in multimap,
// so duplicates are allowed and counted
i = m1.count(1);
cout << "The number of elements in m1 with a sort key of 1 is: "
<< i << "." << endl;
i = m1.count(2);
cout << "The number of elements in m1 with a sort key of 2 is: "
<< i << "." << endl;
i = m1.count(3);
cout << "The number of elements in m1 with a sort key of 3 is: "
<< i << "." << endl;
return;
/*
The number of elements in m1 with a sort key of 1 is: 2.
The number of elements in m1 with a sort key of 2 is: 2.
The number of elements in m1 with a sort key of 3 is: 0.
请按任意键继续. . .
*/
}
//返回multimap是否为空
void mulitmap_empty(void)
{
using namespace std;
multimap <int, int> m1, m2;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 1));
if (m1.empty())
cout << "The multimap m1 is empty." << endl;
else
cout << "The multimap m1 is not empty." << endl;
if (m2.empty())
cout << "The multimap m2 is empty." << endl;
else
cout << "The multimap m2 is not empty." << endl;
return;
/*
The multimap m1 is not empty.
The multimap m2 is empty.
请按任意键继续. . .
*/
}
//返回地址multimap中取得成功的最后一个元素的位置的迭代器
void mulitmap_end(void)
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::iterator m1_Iter;
multimap <int, int> ::const_iterator m1_cIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
m1_cIter = m1.end();
m1_cIter--;
cout << "The value of last element of m1 is "
<< m1_cIter->second << endl;
m1_Iter = m1.end();
m1_Iter--;
m1.erase(m1_Iter);
// The following 2 lines would err because the iterator is const
// m1_cIter = m1.end ( );
// m1_cIter--;
// m1.erase ( m1_cIter );
m1_cIter = m1.end();
m1_cIter--;
cout << "The value of last element of m1 is now "
<< m1_cIter->second << endl;
return;
/*
The value of last element of m1 is 30
The value of last element of m1 is now 20
请按任意键继续. . .
*/
}
//发现的元素，其中的元素的键相匹配的指定值的范围内
void mulitmap_equal_range(void)
{
using namespace std;
typedef multimap <int, int, less<int> > IntMMap;
IntMMap m1;
multimap <int, int> ::const_iterator m1_RcIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
pair <IntMMap::const_iterator, IntMMap::const_iterator> p1, p2;
p1 = m1.equal_range(2);
cout << "The lower bound of the element with "
<< "a key of 2 in the multimap m1 is: "
<< p1.first->second << "." << endl;
cout << "The upper bound of the element with "
<< "a key of 2 in the multimap m1 is: "
<< p1.second->second << "." << endl;
// Compare the upper_bound called directly
m1_RcIter = m1.upper_bound(2);
cout << "A direct call of upper_bound( 2 ) gives "
<< m1_RcIter->second << "," << endl
<< " matching the 2nd element of the pair"
<< " returned by equal_range( 2 )." << endl;
p2 = m1.equal_range(4);
// If no match is found for the key,
// both elements of the pair return end( )
if ((p2.first == m1.end()) && (p2.second == m1.end()))
cout << "The multimap m1 doesn't have an element "
<< "with a key less than 4." << endl;
else
cout << "The element of multimap m1 with a key >= 40 is: "
<< p1.first->first << "." << endl;
return;
/*
The lower bound of the element with a key of 2 in the multimap m1 is: 20.
The upper bound of the element with a key of 2 in the multimap m1 is: 30.
A direct call of upper_bound( 2 ) gives 30,
matching the 2nd element of the pair returned by equal_range( 2 ).
The multimap m1 doesn't have an element with a key less than 4.
请按任意键继续. . .
*/
}
//删除元素或一个范围内指定位置multimap中的元素或删除匹配指定键的元素
void muiltmap_erase(void)
{
using namespace std;
multimap<int, int> m1, m2, m3;
multimap<int, int> ::iterator pIter, Iter1, Iter2;
int i;
multimap<int, int>::size_type n;
typedef pair<int, int> Int_Pair;
for (i = 1; i < 5; i++)
{
m1.insert(Int_Pair(i, i));
m2.insert(Int_Pair(i, i*i));
m3.insert(Int_Pair(i, i - 1));
}
// The 1st member function removes an element at a given position
Iter1 = ++m1.begin();
m1.erase(Iter1);
cout << "After the 2nd element is deleted, "
<< "the multimap ms1 is:";
for (pIter = m1.begin(); pIter != m1.end(); pIter++)
cout << " " << pIter->second;
cout << "." << endl;
// The 2nd member function removes elements
// in the range [_First, _Last)
Iter1 = ++m2.begin();
Iter2 = --m2.end();
m2.erase(Iter1, Iter2);
cout << "After the middle two elements are deleted, "
<< "the multimap m2 is:";
for (pIter = m2.begin(); pIter != m2.end(); pIter++)
cout << " " << pIter->second;
cout << "." << endl;
// The 3rd member function removes elements with a given _Key
m3.insert(Int_Pair(2, 5));
n = m3.erase(2);
cout << "After the element with a key of 2 is deleted,\n"
<< "the multimap m3 is:";
for (pIter = m3.begin(); pIter != m3.end(); pIter++)
cout << " " << pIter->second;
cout << "." << endl;
// The 3rd member function returns the number of elements removed
cout << "The number of elements removed from m3 is: "
<< n << "." << endl;
// The dereferenced iterator can also be used to specify a key
Iter1 = ++m3.begin();
m3.erase(Iter1);
cout << "After another element with a key equal to that"
<< endl;
cout << "of the 2nd element is deleted, "
<< "the multimap m3 is:";
for (pIter = m3.begin(); pIter != m3.end(); pIter++)
cout << " " << pIter->second;
cout << "." << endl;
return;
/*
After the 2nd element is deleted, the multimap ms1 is: 1 3 4.
After the middle two elements are deleted, the multimap m2 is: 1 16.
After the element with a key of 2 is deleted,
the multimap m3 is: 0 2 3.
The number of elements removed from m3 is: 2.
After another element with a key equal to that
of the 2nd element is deleted, the multimap m3 is: 0 3.
请按任意键继续. . .
*/
}
//返回迭代寻址在具有关键相当于一个指定键的multimap中一个元件的第一位置
void muiltmap_find(void)
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::const_iterator m1_AcIter, m1_RcIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 20));
m1.insert(Int_Pair(3, 30));
m1_RcIter = m1.find(2);
cout << "The element of multimap m1 with a key of 2 is: "
<< m1_RcIter->second << "." << endl;
m1_RcIter = m1.find(3);
cout << "The first element of multimap m1 with a key of 3 is: "
<< m1_RcIter->second << "." << endl;
// If no match is found for the key, end( ) is returned
m1_RcIter = m1.find(4);
if (m1_RcIter == m1.end())
cout << "The multimap m1 doesn't have an element "
<< "with a key of 4." << endl;
else
cout << "The element of multimap m1 with a key of 4 is: "
<< m1_RcIter->second << "." << endl;
// The element at a specific location in the multimap can be
// found using a dereferenced iterator addressing the location
m1_AcIter = m1.end();
m1_AcIter--;
m1_RcIter = m1.find(m1_AcIter->first);
cout << "The first element of m1 with a key matching"
<< endl << "that of the last element is: "
<< m1_RcIter->second << "." << endl;
// Note that the first element with a key equal to
// the key of the last element is not the last element
if (m1_RcIter == --m1.end())
cout << "This is the last element of multimap m1."
<< endl;
else
cout << "This is not the last element of multimap m1."
<< endl;
return;
/*
The element of multimap m1 with a key of 2 is: 20.
The first element of multimap m1 with a key of 3 is: 20.
The multimap m1 doesn't have an element with a key of 4.
The first element of m1 with a key matching
that of the last element is: 20.
This is not the last element of multimap m1.
请按任意键继续. . .
*/
}
//返回用于构造multimap中的分配对象的副本
void muiltmap_get_allocator(void)
{
using namespace std;
multimap <int, int>::allocator_type m1_Alloc;
multimap <int, int>::allocator_type m2_Alloc;
multimap <int, double>::allocator_type m3_Alloc;
multimap <int, int>::allocator_type m4_Alloc;
// The following lines declare objects
// that use the default allocator.
multimap <int, int> m1;
multimap <int, int, allocator<int> > m2;
multimap <int, double, allocator<double> > m3;
m1_Alloc = m1.get_allocator();
m2_Alloc = m2.get_allocator();
m3_Alloc = m3.get_allocator();
cout << "The number of integers that can be allocated"
<< endl << "before free memory is exhausted: "
<< m2.max_size() << ".\n" << endl;
cout << "The number of doubles that can be allocated"
<< endl << "before free memory is exhausted: "
<< m3.max_size() << ".\n" << endl;
// The following line creates a multimap m4
// with the allocator of multimap m1.
map <int, int> m4(less<int>(), m1_Alloc);
m4_Alloc = m4.get_allocator();
// Two allocators are interchangeable if
// storage allocated from each can be
// deallocated via the other
if (m1_Alloc == m4_Alloc)
{
cout << "The allocators are interchangeable."
<< endl;
}
else
{
cout << "The allocators are not interchangeable."
<< endl;
}
return;
/*
The number of integers that can be allocated
before free memory is exhausted: 178956970.
The number of doubles that can be allocated
before free memory is exhausted: 134217727.
The allocators are interchangeable.
请按任意键继续. . .
*/
}
//插入一个元素或一定范围内的元素到multimap中的
void muiltmap_insert(void)
{
using namespace std;
multimap <int, int>::iterator m1_pIter, m2_pIter;
multimap <int, int> m1, m2;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
cout << "The original key values of m1 =";
for (m1_pIter = m1.begin(); m1_pIter != m1.end(); m1_pIter++)
cout << " " << m1_pIter->first;
cout << "." << endl;
cout << "The original mapped values of m1 =";
for (m1_pIter = m1.begin(); m1_pIter != m1.end(); m1_pIter++)
cout << " " << m1_pIter->second;
cout << "." << endl;
m1.insert(Int_Pair(1, 10));
// The hint version of insert
m1.insert(--m1.end(), Int_Pair(4, 40));
cout << "After the insertions, the key values of m1 =";
for (m1_pIter = m1.begin(); m1_pIter != m1.end(); m1_pIter++)
cout << " " << m1_pIter->first;
cout << "," << endl;
cout << " and the mapped values of m1 =";
for (m1_pIter = m1.begin(); m1_pIter != m1.end(); m1_pIter++)
cout << " " << m1_pIter->second;
cout << "." << endl;
m2.insert(Int_Pair(10, 100));
// The templatized version inserting a range
m2.insert(++m1.begin(), --m1.end());
cout << "After the insertions, the key values of m2 =";
for (m2_pIter = m2.begin(); m2_pIter != m2.end(); m2_pIter++)
cout << " " << m2_pIter->first;
cout << "," << endl;
cout << " and the mapped values of m2 =";
for (m2_pIter = m2.begin(); m2_pIter != m2.end(); m2_pIter++)
cout << " " << m2_pIter->second;
cout << "." << endl;
return;
/*
The original key values of m1 = 1 2 3.
The original mapped values of m1 = 10 20 30.
After the insertions, the key values of m1 = 1 1 2 3 4,
and the mapped values of m1 = 10 10 20 30 40.
After the insertions, the key values of m2 = 1 2 3 10,
and the mapped values of m2 = 10 20 30 100.
请按任意键继续. . .
*/
}
//检索用于multimap中的命令的键的比较对象的副本
void muiltmap_key_comp(void)
{
using namespace std;
multimap <int, int, less<int> > m1;
multimap <int, int, less<int> >::key_compare kc1 = m1.key_comp();
bool result1 = kc1(2, 3);
if (result1 == true)
{
cout << "kc1( 2,3 ) returns value of true, "
<< "where kc1 is the function object of m1."
<< endl;
}
else
{
cout << "kc1( 2,3 ) returns value of false "
<< "where kc1 is the function object of m1."
<< endl;
}
multimap <int, int, greater<int> > m2;
multimap <int, int, greater<int> >::key_compare kc2 = m2.key_comp();
bool result2 = kc2(2, 3);
if (result2 == true)
{
cout << "kc2( 2,3 ) returns value of true, "
<< "where kc2 is the function object of m2."
<< endl;
}
else
{
cout << "kc2( 2,3 ) returns value of false, "
<< "where kc2 is the function object of m2."
<< endl;
}
return;
/*
kc1( 2,3 ) returns value of true, where kc1 is the function object of m1.
kc2( 2,3 ) returns value of false, where kc2 is the function object of m2.
请按任意键继续. . .
*/
}
//返回一个迭代到第一元件multimap中的，与一个键比指定的键等于或大于
void muiltmap_lower_bound(void)
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::const_iterator m1_AcIter, m1_RcIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 20));
m1.insert(Int_Pair(3, 30));
m1_RcIter = m1.lower_bound(2);
cout << "The element of multimap m1 with a key of 2 is: "
<< m1_RcIter->second << "." << endl;
m1_RcIter = m1.lower_bound(3);
cout << "The first element of multimap m1 with a key of 3 is: "
<< m1_RcIter->second << "." << endl;
// If no match is found for the key, end( ) is returned
m1_RcIter = m1.lower_bound(4);
if (m1_RcIter == m1.end())
cout << "The multimap m1 doesn't have an element "
<< "with a key of 4." << endl;
else
cout << "The element of multimap m1 with a key of 4 is: "
<< m1_RcIter->second << "." << endl;
// The element at a specific location in the multimap can be
// found using a dereferenced iterator addressing the location
m1_AcIter = m1.end();
m1_AcIter--;
m1_RcIter = m1.lower_bound(m1_AcIter->first);
cout << "The first element of m1 with a key matching\n"
<< "that of the last element is: "
<< m1_RcIter->second << "." << endl;
// Note that the first element with a key equal to
// the key of the last element is not the last element
if (m1_RcIter == --m1.end())
cout << "This is the last element of multimap m1."
<< endl;
else
cout << "This is not the last element of multimap m1."
<< endl;
return;
/*
The element of multimap m1 with a key of 2 is: 20.
The first element of multimap m1 with a key of 3 is: 20.
The multimap m1 doesn't have an element with a key of 4.
The first element of m1 with a key matching
that of the last element is: 20.
This is not the last element of multimap m1.
请按任意键继续. . .
*/
}
//返回multimap中的最大长度
void muiltmap_max_size(void)
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::size_type i;
i = m1.max_size();
cout << "The maximum possible length "
<< "of the multimap is " << i << "." << endl;
return;
/*
The maximum possible length of the multimap is 178956970.
请按任意键继续. . .
*/
}
//返回一个迭代解决的第一个元素在逆转多重映射
void muiltmap_rbegin(void)
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::iterator m1_Iter;
multimap <int, int> ::reverse_iterator m1_rIter;
multimap <int, int> ::const_reverse_iterator m1_crIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
m1_rIter = m1.rbegin();
cout << "The first element of the reversed multimap m1 is "
<< m1_rIter->first << "." << endl;
// begin can be used to start an iteration
// throught a multimap in a forward order
cout << "The multimap is: ";
for (m1_Iter = m1.begin(); m1_Iter != m1.end(); m1_Iter++)
cout << m1_Iter->first << " ";
cout << "." << endl;
// rbegin can be used to start an iteration
// throught a multimap in a reverse order
cout << "The reversed multimap is: ";
for (m1_rIter = m1.rbegin(); m1_rIter != m1.rend(); m1_rIter++)
cout << m1_rIter->first << " ";
cout << "." << endl;
// A multimap element can be erased by dereferencing its key
m1_rIter = m1.rbegin();
m1.erase(m1_rIter->first);
m1_rIter = m1.rbegin();
cout << "After the erasure, the first element "
<< "in the reversed multimap is "
<< m1_rIter->first << "." << endl;
return;
/*
The first element of the reversed multimap m1 is 3.
The multimap is: 1 2 3 .
The reversed multimap is: 3 2 1 .
After the erasure, the first element in the reversed multimap is 2.
请按任意键继续. . .
*/
}
//返回解决了一个逆转多重映射成功的最后一个元素的位置的迭代器
void muiltmap_rend(void)
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::iterator m1_Iter;
multimap <int, int> ::reverse_iterator m1_rIter;
multimap <int, int> ::const_reverse_iterator m1_crIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
m1_rIter = m1.rend();
m1_rIter--;
cout << "The last element of the reversed multimap m1 is "
<< m1_rIter->first << "." << endl;
// begin can be used to start an iteration
// throught a multimap in a forward order
cout << "The multimap is: ";
for (m1_Iter = m1.begin(); m1_Iter != m1.end(); m1_Iter++)
cout << m1_Iter->first << " ";
cout << "." << endl;
// rbegin can be used to start an iteration
// throught a multimap in a reverse order
cout << "The reversed multimap is: ";
for (m1_rIter = m1.rbegin(); m1_rIter != m1.rend(); m1_rIter++)
cout << m1_rIter->first << " ";
cout << "." << endl;
// A multimap element can be erased by dereferencing to its key
m1_rIter = --m1.rend();
m1.erase(m1_rIter->first);
m1_rIter = m1.rend();
m1_rIter--;
cout << "After the erasure, the last element "
<< "in the reversed multimap is "
<< m1_rIter->first << "." << endl;
return;
/*
The last element of the reversed multimap m1 is 1.
The multimap is: 1 2 3 .
The reversed multimap is: 3 2 1 .
After the erasure, the last element in the reversed multimap is 2.
请按任意键继续. . .
*/
}
//返回multimap中元素的数量
void muiltmap_size(void)
{
using namespace std;
multimap<int, int> m1, m2;
multimap<int, int>::size_type i;
typedef pair<int, int> Int_Pair;
m1.insert(Int_Pair(1, 1));
i = m1.size();
cout << "The multimap length is " << i << "." << endl;
m1.insert(Int_Pair(2, 4));
i = m1.size();
cout << "The multimap length is now " << i << "." << endl;
return;
/*
The multimap length is 1.
The multimap length is now 2.
请按任意键继续. . .
*/
}
//交换两个muiltmap的元素
void muiltmap_swap(void)
{
using namespace std;
multimap <int, int> m1, m2, m3;
multimap <int, int>::iterator m1_Iter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
m2.insert(Int_Pair(10, 100));
m2.insert(Int_Pair(20, 200));
m3.insert(Int_Pair(30, 300));
cout << "The original multimap m1 is:";
for (m1_Iter = m1.begin(); m1_Iter != m1.end(); m1_Iter++)
cout << " " << m1_Iter->second;
cout << "." << endl;
// This is the member function version of swap
m1.swap(m2);
cout << "After swapping with m2, multimap m1 is:";
for (m1_Iter = m1.begin(); m1_Iter != m1.end(); m1_Iter++)
cout << " " << m1_Iter->second;
cout << "." << endl;
// This is the specialized template version of swap
swap(m1, m3);
cout << "After swapping with m3, multimap m1 is:";
for (m1_Iter = m1.begin(); m1_Iter != m1.end(); m1_Iter++)
cout << " " << m1_Iter->second;
cout << "." << endl;
return;
/*
The original multimap m1 is: 10 20 30.
After swapping with m2, multimap m1 is: 100 200.
After swapping with m3, multimap m1 is: 300.
请按任意键继续. . .
*/
}
//返回一个迭代器的第一个元素multimap中以关键比指定的键更大
void muiltmap_upper_bound(void)
{
using namespace std;
multimap <int, int> m1;
multimap <int, int> ::const_iterator m1_AcIter, m1_RcIter;
typedef pair <int, int> Int_Pair;
m1.insert(Int_Pair(1, 10));
m1.insert(Int_Pair(2, 20));
m1.insert(Int_Pair(3, 30));
m1.insert(Int_Pair(3, 40));
m1_RcIter = m1.upper_bound(1);
cout << "The 1st element of multimap m1 with "
<< "a key greater than 1 is: "
<< m1_RcIter->second << "." << endl;
m1_RcIter = m1.upper_bound(2);
cout << "The first element of multimap m1 with a key "
<< " greater than 2 is: "
<< m1_RcIter->second << "." << endl;
// If no match is found for the key, end( ) is returned
m1_RcIter = m1.lower_bound(4);
if (m1_RcIter == m1.end())
cout << "The multimap m1 doesn't have an element "
<< "with a key of 4." << endl;
else
cout << "The element of multimap m1 with a key of 4 is: "
<< m1_RcIter->second << "." << endl;
// The element at a specific location in the multimap can be
// found using a derefenced iterator addressing the location
m1_AcIter = m1.begin();
m1_RcIter = m1.upper_bound(m1_AcIter->first);
cout << "The first element of m1 with a key greater than\n"
<< "that of the initial element of m1 is: "
<< m1_RcIter->second << "." << endl;
return;
/*
The 1st element of multimap m1 with a key greater than 1 is: 20.
The first element of multimap m1 with a key greater than 2 is: 30.
The multimap m1 doesn't have an element with a key of 4.
The first element of m1 with a key greater than
that of the initial element of m1 is: 20.
请按任意键继续. . .
*/
}
//成员函数返回一个功能对象，通过比较它们的键值确定multimap中的元素的顺序
void muiltmap_value_comp(void)
{
using namespace std;
multimap <int, int, less<int> > m1;
multimap <int, int, less<int> >::value_compare vc1 = m1.value_comp();
multimap<int, int>::iterator Iter1, Iter2;
Iter1 = m1.insert(multimap <int, int> ::value_type(1, 10));
Iter2 = m1.insert(multimap <int, int> ::value_type(2, 5));
if (vc1(*Iter1, *Iter2) == true)
{
cout << "The element ( 1,10 ) precedes the element ( 2,5 )."
<< endl;
}
else
{
cout << "The element ( 1,10 ) does "
<< "not precede the element ( 2,5 )."
<< endl;
}
if (vc1(*Iter2, *Iter1) == true)
{
cout << "The element ( 2,5 ) precedes the element ( 1,10 )."
<< endl;
}
else
{
cout << "The element ( 2,5 ) does "
<< "not precede the element ( 1,10 )."
<< endl;
}
return;
/*
The element ( 1,10 ) precedes the element ( 2,5 ).
The element ( 2,5 ) does not precede the element ( 1,10 ).
请按任意键继续. . .
*/
}