C++实现每隔一段时间，向txt文件中写入数据

//
// Created by funnywii on 2023/4/6.
// To save variables in a txt file
//

#include <fstream> // c++文件操作
#include <sys/time.h>  // get time
#include <unistd.h>
#include <iostream>
#include <time.h>

using namespace std;

bool saveTxtFile(string filename,bool bIfClear, int iTimeSpan){
    ofstream out_txt_file;
    if (bIfClear == true){// clear the previous content
        out_txt_file.open(filename, ios::out | ios::trunc);
    }
    else{                 // reserve the previous content
        out_txt_file.open(filename, ios::binary | ios::app | ios::in | ios::out);
    }
    out_txt_file << fixed;

    struct timeval tv; //start time

    time_t first,second;
    first=time(NULL);
    second=time(NULL);
    // Header
    out_txt_file << "  Time  " << "    " << "  Speed  " << "    " << "  Direction  " << std::endl;
    // 保存数据到文件中
    while(1) 
    {
        second=time(NULL);
        if(difftime(second,first)==iTimeSpan){
            time_t now = time(0);
            // 把 now 转换为字符串形式
            tm *ltm = localtime(&now);

            out_txt_file << ltm->tm_hour << ":" << ltm->tm_min << ":" << ltm->tm_sec << endl;
            cout << "done" << endl;
            first=time(NULL);
        }
    }

    // 关闭文件
    out_txt_file.close();
    return true;
}