boost的bimap相当于STL的map的升级版本, 具有双向映射. 学过STL的map的童鞋很容易掌握它的使用.不过, 差别肯定是有的. 因为它是双向的, 所以有左右之分. 如:
boost::bimap<int,int> bm;
bm.left就相当于stl的map, bm.right就是把stl中的key-value键值对反过来, 变成value-key, 它相应的first和second也就变成了value和key.
bimap是boost中很重要的一个容器，可以进行双向的查找和替换，这样弥补了如果map和multimap需要找到data所对应的键值。循环遍历元素，才能找到相应的键值，再删除，最后替换的不足。
参考代码1如下:
#include <string>
#include <iostream>
#include <boost/bimap.hpp>
template< class MapType >
void print_map(const MapType & map,
const std::string & separator,
std::ostream & os )
{
typedef typename MapType::const_iterator const_iterator;
for( const_iterator i = map.begin(), iend = map.end(); i != iend; ++i )
{
os << i->first << separator << i->second << std::endl;
}
}
int main()
{
// Soccer World cup
typedef boost::bimap< std::string, int > results_bimap;
typedef results_bimap::value_type position;
results_bimap results;
results.insert( position("Argentina" ,1) );
results.insert( position("Spain" ,2) );
results.insert( position("Germany" ,3) );
results.insert( position("France" ,4) );
std::cout << "The number of countries is " << results.size()
<< std::endl;
std::cout << "The winner is " << results.right.at(1)
<< std::endl
<< std::endl;
std::cout << "Countries names ordered by their final position:"
<< std::endl;
// results.right works like a std::map< int, std::string >
print_map( results.right, ") ", std::cout );
std::cout << std::endl
<< "Countries names ordered alphabetically along with"
"their final position:"
<< std::endl;
// results.left works like a std::map< std::string, int >
print_map( results.left, " ends in position ", std::cout );
return 0;
}
输出结果如下:
The output of this program will be the following:
The number of countries is 4
The winner is Argentina
Countries names ordered by their final position:
1) Argentina
2) Spain
3) Germany
4) France
Countries names ordered alphabetically along with their final position:
Argentina ends in position 1
France ends in position 4
Germany ends in position 3
Spain ends in position 2
参考代码二:
// Boost.Bimap
//
// Copyright (c) 2006-2007 Matias Capeletto
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
// VC++ 8.0 warns on usage of certain Standard Library and API functions that
// can be cause buffer overruns or other possible security issues if misused.
// See http://msdn.microsoft.com/msdnmag/issues/05/05/SafeCandC/default.aspx
// But the wording of the warning is misleading and unsettling, there are no
// portable alternative functions, and VC++ 8.0's own libraries use the
// functions in question. So turn off the warnings.
#define _CRT_SECURE_NO_DEPRECATE
#define _SCL_SECURE_NO_DEPRECATE
// Boost.Bimap Example
//-----------------------------------------------------------------------------
#include <boost/config.hpp>
#include <iostream>
#include <boost/tokenizer.hpp>
#include <boost/bimap/bimap.hpp>
#include <boost/bimap/unordered_set_of.hpp>
#include <boost/bimap/list_of.hpp>
using namespace boost::bimaps;
struct counter {
counter() : c(0) {}
counter& operator++() { ++c; return *this; }
unsigned int operator++(int) { return c++; }
operator const unsigned int() const { return c; }
private:
unsigned int c;
};
int main()
{
//[ code_repetitions_counter
typedef bimap
<
unordered_set_of< std::string >,
list_of< counter > /*< `counter` is an integer that is initialized
in zero in the constructor >*/
> word_counter;
typedef boost::tokenizer<boost::char_separator<char> > text_tokenizer;
std::string text=
"Relations between data in the STL are represented with maps."
"A map is a directed relation, by using it you are representing "
"a mapping. In this directed relation, the first type is related to "
"the second type but it is not true that the inverse relationship "
"holds. This is useful in a lot of situations, but there are some "
"relationships that are bidirectional by nature.";
// feed the text into the container
word_counter wc;
text_tokenizer tok(text,boost::char_separator<char>(" tn.,;:!?'"-"));
for( text_tokenizer::const_iterator it = tok.begin(), it_end = tok.end();
it != it_end ; ++it )
{
/*<< Because the right collection type is `list_of`, the right data
is not used a key and can be modified in the same way as with
standard maps. >>*/
++ wc.left[*it];
}
// list words with counters by order of appearance
/*<< When we insert the elements using the left map view, the element
is inserted at the end of the list. >>*/
for( word_counter::right_const_iterator
wit = wc.right.begin(), wit_end = wc.right.end();
wit != wit_end; ++wit )
{
std::cout << wit->second << ": " << wit->first;
}
//]
return 0;
}
