Classification and test a variety of containers (four) - set

set and multiset that the key to the former value Do not repeat , when it is inserted using a random number as its elements, the elements will be rejected repeated encounters inserted (but the program does not crash).

 

 Routine

#include<stdexcept>
#include<string>
#include<cstdlib>
#include<cstdio>
#include<algorithm>
#include<iostream>
#include<ctime>
#include<set>
using namespace std;
long get_a_target_long()
{
	long target = 0;
	cout<<"target(0~"<<RAND_MAX<<"):";
	cin>>target;
	return target;
}
string get_a_target_string()
{
	long target = 0;
	char buf[10];
	cout<<"target(0~"<<RAND_MAX<<"):";
	cin>>target;
	snprintf(buf, 10, "%ld", target);
	return string(buf);
}
int compareLongs(const void* a, const void* b)
{
	return (*(long*)a - *(long*)b);
}

int compareStrings(const void *a, const void *b)
{
	if(*(string*)a > *(string*)b)
		return 1;
	else if(*(string*)a < *(string*)b)
		return -1;
	else
		return 0;
}
void test_set(long& value)
{
	cout << "\ntest_set().......... \n";

	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)); //重复元素会被拒绝插入    					
		}
		catch(exception& p) 
		{
			cout << "i=" << i << " " << p.what() << endl;	
			abort();
		}
	}
	cout << "milli-seconds : " << (clock()-timeStart) << endl;		
	cout << "set.size()= " << c.size() << endl;//元素个数
	cout << "set.max_size()= " << c.max_size() << endl;	   //和计算机内存大小相关

	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;	
	}							
}		
int main()
{
	long int value;
	cout<<"how many elements: ";
	cin>>value;
	test_set(value);
	return 0;
}

 See if our forecast of operating results and as

 

 It requires the insertion of one million elements, but because the set itself is not allowed to duplicate the characteristics of the actual inserted only 998,385 elements.