save data to csv

// elapse.h

#ifndef  __ELAPSE_MILLSEC_H__
#define  __ELAPSE_MILLSEC_H__

//#include <iostream>  
#include <chrono>  
#include <iomanip> // 用于设置输出流的格式  
using namespace std;
//计算耗时
class ElapseMillsec{
public:

    ElapseMillsec(std::string comment);

    ElapseMillsec();
    ~ElapseMillsec();

private:
    std::string m_comment="";
    std::chrono::high_resolution_clock::time_point m_Start;
    std::chrono::high_resolution_clock::time_point m_End;
};

#endif

// elapse.cpp

#include "elapse.h"

ElapseMillsec::ElapseMillsec(std::string comment):m_comment(comment){
  m_Start = std::chrono::high_resolution_clock::now(); // 获取开始时间  
}

ElapseMillsec::ElapseMillsec(){
  m_Start = std::chrono::high_resolution_clock::now(); // 获取开始时间  
}

ElapseMillsec::~ElapseMillsec(){
    m_End = std::chrono::high_resolution_clock::now(); // 获取结束时间  
    // 计算持续时间  
    std::chrono::duration<double, std::milli> elapsed = m_End - m_Start;  
    // 输出执行时间，以毫秒为单位  
    printf("%s cost %f milliseconds.\r\n", m_comment.c_str(), elapsed.count());
}

// save_csv.cpp

#include "elapse.h"
#include <iostream>

#include <vector>
#include <fstream>


typedef struct{
    int iID = 0;
    float fMaxTemp = 0.0f;
    float fMinTemp = 0.0f;
    float fAvgTemp = 0.0f;
    std::string strName="";

}tempDef;

void test(){
    const int iMaxSize = 1000000;
    std::vector<tempDef> vecList;

    // add data to vector
    {
        ElapseMillsec  elap_vecpush("elap_vecpush");  // 211ms
        vecList.reserve(iMaxSize*1.2);
        for(int i=0;i<iMaxSize;i++){
            tempDef td;
            td.iID = i;
            td.fMaxTemp = i+0.1f;
            td.fMinTemp = i+0.1f;
            td.fAvgTemp = i+0.1f;
            td.strName = std::string("test_") + std::to_string(i);
            vecList.push_back(td);
        }
    }

    // save data to csv
    {
        ElapseMillsec  elap_save("elap_save");

        // 如果文件不存在则创建；如果存在则覆盖
        std::ofstream ofs("test.csv", std::ios::out); // 2546ms --> 100w data -->也和设备性能有关系
        ofs << "id,name,max,min,avg\n";
        for(auto& td : vecList){
            ofs << td.iID << "," << td.strName << "," << td.fMaxTemp << "," << td.fMinTemp << "," << td.fAvgTemp << "\n";
        }
        ofs.close();
        std::cout << "save done" << std::endl;
    }

}
int main(){
    test();
    return 0;
}

目前，在我电脑的虚拟机上面的运行情况如下：

100w条数据

数据 加入到vector，耗时：211ms

数据写入到 cvs 文件，耗时：2546ms

100w条数据，文件大小：40044470 byte(38.1Mb)