Classes with file creation and adding time values (linux - g++)

#include <iostream>
#include <stdio.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <string.h>
using namespace std;


class now_Time
{
    private:
    time_t my_time;
    char *now_time;
    public:
    now_Time()
    {
        my_time=time(NULL);
        now_time=asctime(localtime(&my_time));
    }
    char *give_Time()
    {
        return now_time;
    }
};
class uptime_Time
{
    private:
    FILE *uptime_file;
    char *path;
    double real_time;
    double free_time;
    public:
    uptime_Time()
    {
        path="/proc/uptime";
        uptime_file=fopen(path,"r");
        fscanf(uptime_file,"%1f %1f\n",&real_time,&free_time);
    }
    int give_real_Time()
    {
        return (int) real_time;
    }
    int give_free_Time()
    {
        return (int) free_time;
    }
};

class new_file_with_Infos
{
    private:
    char *name_file;
    size_t size_class_time;
    size_t size_free_time;
    size_t size_real_time;
    int file;
    mode_t mode_value;
    public:
    new_file_with_Infos(char *name)
    {
        name_file=name;
        mode_value=S_IRUSR | S_IROTH | S_IWGRP | S_IRGRP | S_IWUSR;
        file=open(name_file, O_WRONLY | O_EXCL | O_CREAT, mode_value);
        now_Time nT;
        uptime_Time uT;
        size_class_time=strlen(nT.give_Time());
        char *temp_free_time;
        char *temp_real_time;
        snprintf(temp_free_time,sizeof(temp_free_time),"%d",uT.give_free_Time());
        size_free_time=strlen(temp_free_time);
        snprintf(temp_real_time,sizeof(temp_real_time),"%d",uT.give_real_Time());
        size_real_time=strlen(temp_real_time);
   
        write(file,nT.give_Time(),size_class_time);
        write(file,temp_free_time,size_free_time);
        write(file,temp_real_time,size_real_time);
        close(file);
    }
};