C++ invoke other class function

//This is UtilityHelper.h

#include <iostream>
#include <uuid/uuid.h>
#include <ctime>

using namespace std;

class UtilityHelper
{
    public:
    static char *uuidValue;
    static char *dtValue;
    UtilityHelper();
    ~UtilityHelper();
    char *getUuid(); 
    char *getTimeNow();
};

 

The UtilityHelper.cpp which implementation parts of declaration in UtilityHelper.h

#include <UtilityHelper.h>

char * UtilityHelper::uuidValue=(char*)malloc(40);
char * UtilityHelper::dtValue=(char*)malloc(20);

char * UtilityHelper::getTimeNow()
{
    time_t rawTime=time(NULL);
    struct tm tmInfo=*localtime(&rawTime);
    strftime(dtValue,20,"%Y%m%d%H%M%S",&tmInfo);
    return dtValue;
}

char* UtilityHelper::getUuid()
{
    uuid_t newUUID;
    uuid_generate(newUUID);
    uuid_unparse(newUUID,uuidValue);
    return uuidValue;
}

UtilityHelper::UtilityHelper()
{
    cout<<"This is UtilityHelper constructor and now is "<<getTimeNow()<<endl;
}

UtilityHelper::~UtilityHelper()
{
    cout<<"This is UtilityHelper deconstructor and now is "<<getTimeNow()<<endl;
}

 

Invoke in main.cpp

#include <iostream>
#include <uuid/uuid.h>
#include <sstream>
#include <ctime>
#include <unistd.h>
#include <ostream>
#include <fstream>
#include <istream>
#include <random>
#include <vector>
#include "UtilityHelper.h"

void class9();

int main()
{
    class9();
    return 0;
}


void class9()
{
    UtilityHelper uh;
    for(int i=0;i<100;i++)
    {
        cout<<"Index="<<i<<",uuidvalue="<<uh.getUuid()<<",now is "<<uh.getTimeNow()<<endl;
        usleep(100000);
    }
    
    cout<<"Finished in class9() and now is "<<getTimeNow()<<endl;
    free(UtilityHelper::dtValue);
    free(UtilityHelper::uuidValue);
}

Compile via below command,please pay attention to the below command which adds the additional cpp file UtilityHelper.cpp 

g++ -g -std=c++2a -I. h1.cpp UtilityHelper.cpp -o h1 -luuid

Run ./h1