C++之实现快速清空vector以及释放vector内存

#include <iostream>
#include <vector>
#include <string>
#include <Windows.h>
#include <Psapi.h>
#pragma comment(lib, "Psapi.lib")
using namespace std;
//GetCurPorcessMemory
bool GetCurProcessMemory(HANDLE handle, std::wstring& workingSize, std::wstring& peakWorkingSize)
{
	//HANDLE handle = GetCurrentProcess();
	PROCESS_MEMORY_COUNTERS pmc;
	if (GetProcessMemoryInfo(handle, &pmc, sizeof(pmc)))
	{
		int size = pmc.WorkingSetSize/1024;
		wchar_t buf[10] = {0};
		_ltow(size, buf, 10);
		workingSize = std::wstring(buf);
		size = pmc.PeakWorkingSetSize/1024;
		_ltow(size, buf, 10);
		peakWorkingSize = std::wstring(buf);
		return true;
	}
	return false;
}
int _tmain(int argc, _TCHAR* argv[])
{
	std::wstring wszWorking, wszPeakWorking;
	vector<string> ary;
	for (int i=0; i<1000000; i++)
	{
		ary.push_back("hello vector");
	}
	wchar_t wch;
	wcin >> wch;
	GetCurProcessMemory(GetCurrentProcess(), wszWorking, wszPeakWorking);// 此时检查内存情况
	wcout << "Working : " << wszWorking.c_str() << " PeakWorking : " << wszPeakWorking.c_str() << endl;
	wcin >> wch;
	//
	ary.clear();
	wcout << "vector clear" << endl;
	wcout << "vector capacity " << ary.capacity() << endl;	
	GetCurProcessMemory(GetCurrentProcess(), wszWorking, wszPeakWorking);// 此时再次检查
	wcout << "Working : " << wszWorking.c_str() << " PeakWorking : " << wszPeakWorking.c_str() << endl;
	wcin >> wch;
	//vector<string>(ary).swap(ary);
	ary.swap(vector<string>(ary));	
	wcout << "vector swap" << endl;
	wcout << "vector capacity " << ary.capacity() << endl;// 此时容量为0	
	GetCurProcessMemory(GetCurrentProcess(), wszWorking, wszPeakWorking);// 检查内存
	wcout << "Working : " << wszWorking.c_str() << " PeakWorking : " << wszPeakWorking.c_str() << endl;
	wcout << "vector size : " << ary.size() << endl;//0
	//getchar();
	system("pause");
	return 0;
}

//by 鸟哥 清空vector的三种方法
//有疑问请留言或加群 1032082534
#include <iostream>  
#include <vector>
using namespace std;
int main(){
    vector <int> vecInt;
    for (int i=0;i<50;i++)
    {
        vecInt.push_back(i);
    }
    cout<<"capacity:"<<vecInt.capacity();   //j=64
    cout<<"size:"<<vecInt.size();          //i=50           
    cout<<endl;
    //1、使用clear ，清空元素，不回收空间
    vecInt.clear();
    cout<<"capacity:"<<vecInt.capacity();      //j=64
    cout<<"size:"<<vecInt.size();         //i=50
    cout<<endl;
    //2、erase循环删除，不回收空间
    for (int i=0;i<50;i++)
    {
        vecInt.push_back(i);
    }
    for ( vector <int>::iterator iter=vecInt.begin();iter!=vecInt.end();)
    {
        iter=vecInt.erase(iter);
    }
    cout<<"capacity:"<<vecInt.capacity();      //j=64
    cout<<"size:"<<vecInt.size();         //i=50   
    cout<<endl;
    //3、使用swap,清除元素并回收内存
    vector <int>().swap(vecInt);  //清除容器并最小化它的容量，
    //   vecInt.swap(vector<int>()) ;     另一种写法
    cout<<"capacity:"<<vecInt.capacity();      //j=0
    cout<<"size:"<<vecInt.size();         //i=0
    cout<<endl;
}