一：无序容器简介
Unordered Containers也是一种关联式容器。其中元素是分散，没有定性的排列（不是图中那样松散）。其中元素可能在某一次操作后改变原来的位置。
哈希表的链地址法，更能表现其内部实现结构。其中哈希表中表长可以改变，其实现用分配器实现，
为了防止链表过程，效率减低，设置一个值，当链表长度过长时，打散哈希表，重新设置表长，分配位置。
二：性能测试
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <stdio.h>
#include <cstring>
#if _MSC_VER
#define snprintf _snprintf
#endif
using namespace std;
long get_a_target_long()
{
/******变量声明********/
long target = 0;
/**********************/
cout << "targer (0~" << RAND_MAX << "):";
cin >> target;
return target;
}
string get_a_target_string()
{
/******变量声明********/
long target = 0;
char buf[10];
/**********************/
cout << "targer (0~" << RAND_MAX << "):";
cin >> target;
snprintf(buf, 10, "%d", target);
return string(buf);
}
//与后面的比较函数中回调参数对应
int compareLongs(const void* l1, const void* l2)
{
return (*(long*)l1 - *(long*)l2);
}
int compareStrings(const void* s1, const void* s2)
{
if (*(string*)s1 > *(string*)s2)
return 1;
if (*(string*)s1 < *(string*)s2)
return -1;
return 0;
}
公共函数
#include <unordered_set>
//测试unordered_multiset-->元素可以重复
namespace jj12
{
void test_unordered_multiset(long& us_size)
{
cout << "\ntest_unordered_multiset()*******" << endl;
/******变量声明:数组初始********/
char buf[10];
/******变量声明:unordered_multiset初始********/
unordered_multiset<string> ums;
/******变量声明：记录时间********/
clock_t timeStart = clock(); //开始时间
for (long i = 0; i < us_size; i++)
{
try
{
snprintf(buf, 10, "%d", rand());
ums.insert(string(buf));
}
catch (exception& e)
{
cout << e.what() << endl;
cout << "Max_size:" << i << endl;
abort(); //终止
}
}
cout << "inti unordered_multiset use milli-seconds:" << (clock() - timeStart) << endl; //获取初始化数组耗时
cout << "unordered_multiset.size:" << ums.size() << endl; //获取unordered_multiset大小
cout << "unordered_multiset.max_size:" << ums.max_size() << endl; //获取unordered_multiset允许最大长度
cout << "unordered_multiset.bucket_count:" << ums.bucket_count() << endl; //获取篮子数--表长
cout << "unordered_multiset.load_factor:" << ums.load_factor() << endl; //获取加载因子
cout << "unordered_multiset.max_load_factoe:" << ums.max_load_factor() << endl; //获取最大加载因子--1
cout << "unordered_multiset.max_bucket_count:" << ums.max_bucket_count() << endl; //获取存在最大篮子数--表长
//打印前20个篮子
for (int i = 0; i < 20; i++)
cout << "Key #" << i << " has " <<
ums.bucket_size(i) //该篮子中有几个元素
<< " elements" << endl;
/******变量声明：获取我们要查询的数********/
string target = get_a_target_string();
//使用::find方法进行查找
timeStart = clock();
auto pI = find(ums.begin(), ums.end(), target);
cout << "::find(),milli-seconds:" << clock() - timeStart << endl;
if (pI != ums.end())
cout << "found:" << *pI << endl;
else
cout << "not found!" << endl;
//使用unordered_multiset.find查找
timeStart = clock();
pI = ums.find(target); //比::find块得多，直接定位查询，
cout << "unordered_multiset.find(),milli-seconds:" << clock() - timeStart << endl;
if (pI != ums.end())
cout << "found:" << *pI << endl;
else
cout << "not found!" << endl;
}
}
#include <unordered_map>
//测试unordered_multimap-->元素可以重复
namespace jj13
{
void test_unordered_multimap(long& mm_size)
{
cout << "\ntest_unordered_multimap()*******" << endl;
/******变量声明:数组初始********/
char buf[10];
/******变量声明:unordered_multimap初始********/
unordered_multimap<long, string> umm;
/******变量声明：记录时间********/
clock_t timeStart = clock(); //开始时间
for (long i = 0; i < mm_size; i++)
{
try
{
snprintf(buf, 10, "%d", rand());
umm.insert(pair<long, string>(i, string(buf)));
}
catch (exception& e)
{
cout << e.what() << endl;
cout << "Max_size:" << i << endl;
abort(); //终止
}
}
cout << "inti unordered_multimap use milli-seconds:" << (clock() - timeStart) << endl; //获取初始化数组耗时
cout << "unordered_multimap.size:" << umm.size() << endl; //获取unordered_multimap大小
cout << "unordered_multimap.max_size:" << umm.max_size() << endl; //获取unordered_multimap所允许最大
cout << "unordered_multimap.bucket_count:" << umm.bucket_count() << endl; //获取篮子数--表长
cout << "unordered_multimap.load_factor:" << umm.load_factor() << endl; //获取加载因子
cout << "unordered_multimap.max_load_factoe:" << umm.max_load_factor() << endl; //获取最大加载因子--1
cout << "unordered_multimap.max_bucket_count:" << umm.max_bucket_count() << endl; //获取存在最大篮子数--表长
//打印前20个篮子
for (int i = 0; i < 20; i++)
cout << "Key #" << i << " has " <<
umm.bucket_size(i) //该篮子中有几个元素
<< " elements" << endl;
/******变量声明：获取我们要查询的数********/
long target = get_a_target_long(); //根据key查找
//unordered_multimap没有全局::find方法可用，::find找值，multimap找键，两者不同，不可以混用
//使用unordered_multimap.find查找
timeStart = clock();
auto pI = umm.find(target);
cout << "unordered_multimap.find(),milli-seconds:" << clock() - timeStart << endl;
if (pI != umm.end())
cout << "found:" << (*pI).first << ":" << (*pI).second << endl;
else
cout << "not found!" << endl;
}
}
#include <unordered_set>
//测试unordered_set-->元素不可以重复
namespace jj14
{
void test_unordered_set(long& us_size)
{
cout << "\ntest_unordered_set()*******" << endl;
/******变量声明:数组初始********/
char buf[10];
/******变量声明:unordered_set初始********/
unordered_set<string> us;
/******变量声明：记录时间********/
clock_t timeStart = clock(); //开始时间
for (long i = 0; i < us_size; i++)
{
try
{
snprintf(buf, 10, "%d", rand());
us.insert(string(buf));
}
catch (exception& e)
{
cout << e.what() << endl;
cout << "Max_size:" << i << endl;
abort(); //终止
}
}
cout << "inti unordered_multiset use milli-seconds:" << (clock() - timeStart) << endl; //获取初始化数组耗时
cout << "unordered_set.size:" << us.size() << endl; //获取unordered_set大小
cout << "unordered_set.max_size:" << us.max_size() << endl; //获取unordered_set允许最大
cout << "unordered_set.bucket_count:" << us.bucket_count() << endl; //获取篮子数--表长
cout << "unordered_set.load_factor:" << us.load_factor() << endl; //获取加载因子
cout << "unordered_set.max_load_factoe:" << us.max_load_factor() << endl; //获取最大加载因子--1
cout << "unordered_set.max_bucket_count:" << us.max_bucket_count() << endl; //获取存在最大篮子数--表长
//打印前20个篮子
for (int i = 0; i < 20; i++)
cout << "Key #" << i << " has " <<
us.bucket_size(i) //该篮子中有几个元素
<< " elements" << endl;
/******变量声明：获取我们要查询的数********/
string target = get_a_target_string();
//使用::find方法进行查找
timeStart = clock();
auto pI = find(us.begin(), us.end(), target);
cout << "::find(),milli-seconds:" << clock() - timeStart << endl;
if (pI != us.end())
cout << "found:" << *pI << endl;
else
cout << "not found!" << endl;
//使用unordered_set.find查找
timeStart = clock();
pI = us.find(target); //比::find块得多，直接定位查询，
cout << "unordered_set.find(),milli-seconds:" << clock() - timeStart << endl;
if (pI != us.end())
cout << "found:" << *pI << endl;
else
cout << "not found!" << endl;
}
}
#include <unordered_map>
//测试unordered_map-->元素不可以重复
namespace jj15
{
void test_unordered_map(long& um_size)
{
cout << "\ntest_unordered_map()*******" << endl;
/******变量声明:数组初始********/
char buf[10];
/******变量声明:unordered_multimap初始********/
unordered_map<long, string> um;
/******变量声明：记录时间********/
clock_t timeStart = clock(); //开始时间
for (long i = 0; i < um_size; i++)
{
try
{
snprintf(buf, 10, "%d", rand());
um.insert(pair<long, string>(i, string(buf)));
}
catch (exception& e)
{
cout << e.what() << endl;
cout << "Max_size:" << i << endl;
abort(); //终止
}
}
cout << "inti unordered_map use milli-seconds:" << (clock() - timeStart) << endl; //获取初始化数组耗时
cout << "unordered_map.size:" << um.size() << endl; //获取unordered_map大小
cout << "unordered_map.max_size:" << um.max_size() << endl; //获取unordered_map允许最大
cout << "unordered_map.bucket_count:" << um.bucket_count() << endl; //获取篮子数--表长
cout << "unordered_map.load_factor:" << um.load_factor() << endl; //获取加载因子
cout << "unordered_map.max_load_factoe:" << um.max_load_factor() << endl; //获取最大加载因子--1
cout << "unordered_map.max_bucket_count:" << um.max_bucket_count() << endl; //获取存在最大篮子数--表长
//打印前20个篮子
for (int i = 0; i < 20; i++)
cout << "Key #" << i << " has " <<
um.bucket_size(i) //该篮子中有几个元素
<< " elements" << endl;
/******变量声明：获取我们要查询的数********/
long target = get_a_target_long(); //根据key查找
//unordered_map没有全局::find方法可用，::find找值，unordered_map找键，两者不同，不可以混用
//使用unordered_map.find查找
timeStart = clock();
auto pI = um.find(target);
cout << "unordered_map.find(),milli-seconds:" << clock() - timeStart << endl;
if (pI != um.end())
cout << "found:" << (*pI).first << ":" << (*pI).second << endl;
else
cout << "not found!" << endl;
}
}
