侯捷STL学习(二)--序列容器测试

第六节：容器之分类和各种测试（四）

  • stack不提供iterator操作，破坏了容器的独特性，先进先出。

使用容器multiset（允许元素重复）

  • 内部是红黑树，insert操作就保证了排好了序。
  • 标准库有个：：find()函数，大家都可以用。容器本身也有一个c.find()，通过键值对查找非常快！
  • 测试
#include <set>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj06
{
void test_multiset(long& value)
{
	cout << "
test_multiset().......... 
";
	
multiset<string> c;  	
char buf[10];		
clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
        	c.insert(string(buf));     				
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;	
	cout << "multiset.size()= " << c.size() << endl;	
	cout << "multiset.max_size()= " << c.max_size() << endl;	//214748364
	
string target = get_a_target_string();	
	{
    timeStart = clock();
auto pItem = find(c.begin(), c.end(), target);	//比 c.find(...) 慢很多	
	cout << "std::find(), milli-seconds : " << (clock()-timeStart) << endl;		
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}
 	
 	{
    timeStart = clock();		
auto pItem = c.find(target);		//比 std::find(...) 快很多							
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;		 
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}	
	 
	c.clear();
	test_moveable(multiset<MyString>(),multiset<MyStrNoMove>(), value);	 						
}															 
}

使用容器multimap（允许元素重复）

  • 内部是红黑树，key-value键值对。
  • multiset不可用[]做insertion
  • c.insert(pair<long,string>(i,buff))
  • (*pItem).second
  • 测试
#include <map>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj07
{
void test_multimap(long& value)
{
	cout << "
test_multimap().......... 
";
     
multimap<long, string> c;  	
char buf[10];
			
clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
    		//multimap 不可使用 [] 做 insertion 
        	c.insert(pair<long,string>(i,buf));   						
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;	
	cout << "multimap.size()= " << c.size() << endl;
	cout << "multimap.max_size()= " << c.max_size() << endl;	//178956970	
	
long target = get_a_target_long();		
    timeStart = clock();		
auto pItem = c.find(target);								
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;	 
	if (pItem != c.end())
    	cout << "found, value=" << (*pItem).second << endl;
  	else
    	cout << "not found! " << endl;	  
		
	c.clear();		  					
}															 
}

使用unordered_multiset容器

  • 使用hashtable使用分离链地址方法实现
  • gnu C之前的名称hash_multiset
  • unorder_multiset.bucket_count篮子的个数
  • load_factor,max_load_factor,max_bucket_count方法
  • 篮子后面的链表不能太长，元素的个数大于等于篮子的个数，就需要重新分配篮子的大小，重新进行插入元素
  • c.find()容器自身的find操作快很多
  • 测试
#include <unordered_set>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj08
{
void test_unordered_multiset(long& value)
{
	cout << "
test_unordered_multiset().......... 
";
     
unordered_multiset<string> c;  	
char buf[10];
			
clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
        	c.insert(string(buf));   			  		
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
	cout << "unordered_multiset.size()= " << c.size() << endl;
	cout << "unordered_multiset.max_size()= " << c.max_size() << endl;	//357913941
	cout << "unordered_multiset.bucket_count()= " << c.bucket_count() << endl;	
	cout << "unordered_multiset.load_factor()= " << c.load_factor() << endl;	
	cout << "unordered_multiset.max_load_factor()= " << c.max_load_factor() << endl;	
	cout << "unordered_multiset.max_bucket_count()= " << c.max_bucket_count() << endl;				
  	for (unsigned i=0; i< 20; ++i) {
    	cout << "bucket #" << i << " has " << c.bucket_size(i) << " elements.
";
  	}					
				
string target = get_a_target_string();	
	{
    timeStart = clock();
auto pItem = find(c.begin(), c.end(), target);	//比 c.find(...) 慢很多	
	cout << "std::find(), milli-seconds : " << (clock()-timeStart) << endl;	
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}
 
 	{
    timeStart = clock();		
auto pItem = c.find(target);		//比 std::find(...) 快很多							
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;	 
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}		
	 
    c.clear();
	test_moveable(unordered_multiset<MyString>(),unordered_multiset<MyStrNoMove>(), value);		 	 							
}													 
}

使用unordered_multimap容器

  • 测试
#include <unordered_map>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj09
{
void test_unordered_multimap(long& value)
{
	cout << "
test_unordered_multimap().......... 
";
     
unordered_multimap<long, string> c;  	
char buf[10];
			
clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
			//multimap 不可使用 [] 進行 insertion 
			c.insert(pair<long,string>(i,buf));
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
	cout << "unordered_multimap.size()= " << c.size() << endl;	
	cout << "unordered_multimap.max_size()= " << c.max_size() << endl;	//357913941	
	
long target = get_a_target_long();		
    timeStart = clock();		
auto pItem = c.find(target);								
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;		 
	if (pItem != c.end())
    	cout << "found, value=" << (*pItem).second << endl;
  	else
    	cout << "not found! " << endl;		
}															 
}

使用set容器

  • 不允许元素重复
#include <set>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj13
{
void test_set(long& value)
{
	cout << "
test_set().......... 
";
     
set<string> c;  	
char buf[10];

clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
        	c.insert(string(buf));     					
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
	cout << "set.size()= " << c.size() << endl;
	cout << "set.max_size()= " << c.max_size() << endl;	   //214748364
		
string target = get_a_target_string();	
	{
    timeStart = clock();
auto pItem = find(c.begin(), c.end(), target);	//比 c.find(...) 慢很多	
	cout << "std::find(), milli-seconds : " << (clock()-timeStart) << endl;		
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}
 	
 	{
    timeStart = clock();		
auto pItem = c.find(target);		//比 std::find(...) 快很多							
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;		 
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}							
}															 
}

使用map容器

  • 不允许元素键重复
  • c[i]=string(buf)组成pair，允许这样进行插入操作
#include <map>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj14
{
void test_map(long& value)
{
	cout << "
test_map().......... 
";
     
map<long, string> c;  	
char buf[10];
			
clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
			c[i] = string(buf);  					
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;	
	cout << "map.size()= " << c.size() << endl;	
	cout << "map.max_size()= " << c.max_size() << endl;		//178956970
	
long target = get_a_target_long();		
    timeStart = clock();		
auto pItem = c.find(target);								
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;		 
	if (pItem != c.end())
    	cout << "found, value=" << (*pItem).second << endl;
  	else
    	cout << "not found! " << endl;			
    	
    c.clear();					
}															 
}

使用unorder_set容器

#include <unordered_set>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj15
{
void test_unordered_set(long& value)
{
	cout << "
test_unordered_set().......... 
";
     
unordered_set<string> c;  	
char buf[10];
			
clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
        	c.insert(string(buf));    			 		
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
	cout << "unordered_set.size()= " << c.size() << endl;	
	cout << "unordered_set.max_size()= " << c.max_size() << endl;  //357913941
	cout << "unordered_set.bucket_count()= " << c.bucket_count() << endl;	
	cout << "unordered_set.load_factor()= " << c.load_factor() << endl;	
	cout << "unordered_set.max_load_factor()= " << c.max_load_factor() << endl;	
	cout << "unordered_set.max_bucket_count()= " << c.max_bucket_count() << endl;			
  	for (unsigned i=0; i< 20; ++i) {
    	cout << "bucket #" << i << " has " << c.bucket_size(i) << " elements.
";
  	}			
	
string target = get_a_target_string();	
	{
    timeStart = clock();
auto pItem = find(c.begin(), c.end(), target);	//比 c.find(...) 慢很多	
	cout << "std::find(), milli-seconds : " << (clock()-timeStart) << endl;		
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}
 
 	{
    timeStart = clock();		
auto pItem = c.find(target);		//比 std::find(...) 快很多							
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;		 
	if (pItem != c.end())
    	cout << "found, " << *pItem << endl;
  	else
    	cout << "not found! " << endl;	
 	}	
}															 
}

使用unorder_map容器

#include <unordered_map>
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj16
{
void test_unordered_map(long& value)
{
	cout << "
test_unordered_map().......... 
";

unordered_map<long, string> c;  	
char buf[10];
			
clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
			c[i] = string(buf);  		
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
	cout << "unordered_map.size()= " << c.size() << endl;	//357913941
	cout << "unordered_map.max_size()= " << c.max_size() << endl;	
	
long target = get_a_target_long();		
    timeStart = clock();	
//! auto pItem = find(c.begin(), c.end(), target);	//map 不適用 std::find() 			
auto pItem = c.find(target);
						
	cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl;		 
	if (pItem != c.end())
    	cout << "found, value=" << (*pItem).second << endl;
  	else
    	cout << "not found! " << endl;		
}															 
}

hash_set/hash_map/hash_multiset/hash_multimap

  • 包含gnu C的编译器就可以

  • 包含的头文件可能需要修改#include<...>非标准容器，由于时间的原因，没有放在一起,在C++11大会之前就出现了！

  • 测试

/*
以下測試 hash_multiset, hash_multimap 過程中遇到阻礙：
headers <hash_set> 和 <hash_map> 各有兩個，
分別在 ...4.9.2includec++ackward 和 ...4.9.2includec++ext，
不知要用哪一組! 
用 <ext...> 那一組會有問題 
   ...4.9.2includec++ackwardhashtable.h 
   [Error] no match for call to '(const hasher {aka const __gnu_cxx::hash<std::basic_string<char> >}) (const key_type&)'
用 <backward...> 那一組有相同的問題.  
so, 放棄測試 (no insertion or push_back or ...).  
*/

#include <exthash_set>		
    //...4.9.2includec++ackwardackward_warning.h	
	//[Warning] #warning This file includes at least one deprecated or antiquated header 
	//which may be removed without further notice at a future date. 
	//Please use a non-deprecated interface with equivalent functionality instead. 
	//For a listing of replacement headers and interfaces, consult the file backward_warning.h. 
	//To disable this warning use -Wno-deprecated. [-Wcpp]
	
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj11
{
void test_hash_multiset(long& value)
{
	cout << "
test_hash_multiset().......... 
";
   
	__gnu_cxx::hash_multiset<string> c;  	
	char buf[10];
			
    clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
        	//! c.insert(string(buf));     		
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;				
}															 
}
//---------------------------------------------------
#include <exthash_map>
    //...4.9.2includec++ackwardackward_warning.h	
	//[Warning] #warning This file ... (如上個函數所言)
#include <stdexcept>
#include <string>
#include <cstdlib> //abort()
#include <cstdio>  //snprintf()
#include <iostream>
#include <ctime> 
namespace jj12
{
void test_hash_multimap(long& value)
{
	cout << "
test_hash_multimap().......... 
";
     
	__gnu_cxx::hash_multimap<long, string> c;  	
	char buf[10];
			
    clock_t timeStart = clock();								
    for(long i=0; i< value; ++i)
    {
    	try {
    		snprintf(buf, 10, "%d", rand());
        	//c.insert(...   		
		}
		catch(exception& p) {
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
	
    timeStart = clock();								
    //! auto ite = c.find(...
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
}												
}
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原文地址：https://www.cnblogs.com/ranjiewen/p/6942598.html