chapter10-42.cpp

C++STL程序员开发指南

//文件名:CHAPTER10-42.cpp
#pragma warning(disable: 4786)
#include <map>
#include <iostream>
#include <string>

typedef std::multimap<char, std::string> multimap_INT_STR ;
typedef multimap_INT_STR::iterator multimap_ITERATOR ;
typedef multimap_INT_STR::reverse_iterator multimap_REVERSE_ITERATOR ;
typedef std::pair<char, std::string> PAIR_INT_STR ;
template <class ITERATOR>
void print_multimap_item(ITERATOR it)
{	std::cout << (*it).first << ", " << 	(*it).second << std::endl ;}

int main()
{
	//默认构造函数定义变量c1
	multimap_INT_STR c1 ;	
	PAIR_INT_STR pairs[5] = {	PAIR_INT_STR('a', std::string("ATL")),
								PAIR_INT_STR('a', std::string("ADO")),
								PAIR_INT_STR('b', std::string("BASIC")),
								PAIR_INT_STR('c', std::string("COM")),
								PAIR_INT_STR('d', std::string("DAO"))
							};
	//定义变量c2，并且其值通过数组进行初始化
	//multimap_INT_STR c2(pairs, pairs + 5) ;
	multimap_INT_STR c2 ;
	c2.insert(multimap_INT_STR::value_type('a', std::string("ATL"))) ;
	c2.insert(multimap_INT_STR::value_type('a', std::string("ADO"))) ;
	c2.insert(multimap_INT_STR::value_type('b', std::string("BASIC"))) ;
	c2.insert(multimap_INT_STR::value_type('c', std::string("COM"))) ;
	c2.insert(multimap_INT_STR::value_type('d', std::string("DAO"))) ;

	//拷贝型构造函数
	multimap_INT_STR c3(c2) ;
	//利用empty判断c1是否为空
	if(c1.empty())
	{		std::cout << "c1 is empty" << std::endl ;	}
	else
	{		std::cout << "c1 is not empty" << std::endl ;	}
	//利用begin, end返回首末迭代器
	std::cout << "c2 (using begin, end) = " << std::endl ;
	multimap_ITERATOR Iter1 ;
	for(Iter1 = c2.begin(); Iter1 != c2.end(); Iter1++)
	{		print_multimap_item(Iter1) ;	}
	//利用rbegin, rend返回反向首末迭代器
	std::cout << "c2 (using rbegin, rend) = " << std::endl ;
	multimap_REVERSE_ITERATOR RevIter1 ;
	for(RevIter1 = c2.rbegin(); RevIter1 != c2.rend(); RevIter1++)
	{		print_multimap_item(RevIter1) ;	}
	//利用insert插入元素
	Iter1 = c1.insert(multimap_INT_STR::value_type('i', std::string("Internet"))) ;
	if(Iter1 != c1.end())
	{	std::cout << "a pair of key/data was inserted in c1, *Iter1 = " ;
		print_multimap_item(Iter1); 
	}
	else
	{		std::cout << "pair('i', \"Internet\") was not inserted in c1" << std::endl ;	}
	//c1.insert(pairs, pairs + 5) ;
	c1.insert(multimap_INT_STR::value_type('a', std::string("ATL"))) ;
	c1.insert(multimap_INT_STR::value_type('a', std::string("ADO"))) ;
	c1.insert(multimap_INT_STR::value_type('b', std::string("BASIC"))) ;
	c1.insert(multimap_INT_STR::value_type('c', std::string("COM"))) ;
	c1.insert(multimap_INT_STR::value_type('d', std::string("DAO"))) ;

	c1.insert(c1.begin(), PAIR_INT_STR('j', std::string("java"))) ;
	//利用find查找元素
	std::cout << "Does c1 contain any pair with key = j?" << std::endl ;
	Iter1 = c1.find('j') ;
	if(Iter1 != c1.end())
	{
		std::cout << "c1 contains pair:" ;
		print_multimap_item(Iter1) ;
	}
	else
	{		std::cout << "c1 does not contain any element with key = j" << std::endl ;	}
	//根据max_size返回最大元素大小
	std::cout << "max elements which c1 can hold uisng current allocator = "<< c1.max_size() << std::endl ;
	//根据size返回元素大小
	std::cout << "number of elements in c1 = " << c1.size() << std::endl ;
	//利用swap进行元素交换
	c1.swap(c2) ;
	std::cout << "Last key/data pair in c1 = " ;
	print_multimap_item(c1.rbegin()) ;
	//使用clear进行元素清除
	c3.clear() ;
	std::cout << "after calling c3.clear(), number of elements in c3 = " << c3.size() << std::endl ;
	//根据get_allocator获取内存分配器
	multimap_INT_STR::allocator_type a1 = c3.get_allocator() ;
	//key_comp进行键值比较
	multimap_INT_STR::key_compare kc = c1.key_comp() ;
	std::cout << "use function object kc to find less of ('a', 'b')..." << std::endl ;
	if (kc('a', 'b') == true)
		std::cout << "kc('a', 'b') == true, which means 'a' < 'b'" << std::endl ;
	else
		std::cout << "kc('a', 'b') == false, which means 'a' > 'b'" << std::endl ;
	//value_comp进行实值比较
	multimap_INT_STR::value_compare vc = c1.value_comp() ;
	std::cout << "use function object vc to compare char-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返回上迭代器
	Iter1 = c2.upper_bound('c') ;
	std::cout << "first multimap element with key > 'c' = " ;
	print_multimap_item(Iter1) ;
	//lower_bound返回下迭代器
	Iter1 = c2.lower_bound('c') ;
	std::cout << "first multimap element with key 'c' = " ;
	print_multimap_item(Iter1) ;
	//equal_range返回上下迭代器
	std::pair<multimap_ITERATOR, multimap_ITERATOR> pair2 = c2.equal_range('c') ;
	std::cout << "using c2.equal_range('c'),first multimap element with key > 'c' = " ;
	print_multimap_item(pair2.second) ;
	std::cout << "using c2.equal_range('c'), first multimap element with key = 'c' = " ;
	print_multimap_item(pair2.first) ;
//count进行元素统计
	std::cout << "number of pairs in c2 with key 'a' = " << c2.count('a') << std::endl ;
	//erase进行所有元素清除
	c2.erase(c2.begin()) ;
	std::cout << "first key/data pair of c2 is: " ;
	print_multimap_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('j') == 1)
	{		std::cout << "element with key 'j' in c2 was erased" << std::endl ;	}
	else
	{		std::cout << "c2 does not contain any element with key 'j'" << std::endl ;	}	
	return 0 ;
}