C++ struct array with char * properties,convert int to unsigned long long

#include <iostream>
#include <uuid/uuid.h>
#include <ctime>
#include <random>
#include <unistd.h>
#include <string.h>
#include <exception>
#include <typeinfo>
#include <stdexcept>

using namespace std;

static char *dtValue = (char *)malloc(20);
static char *uuidValue = (char *)malloc(40);
char *getTimeNow();
char *getUuidValue3();

struct BookStruct2
{
    unsigned long long BookId;
    char *BookName;
    char *BookTitle;
};
void getStructArray9(struct BookStruct2 *ptr, int len);
void printBookStruct10();

int main()
{
    printBookStruct10();
    return 0;
}

void printBookStruct10()
{
    int len = 10000;
    struct BookStruct2 arr[len];
    getStructArray9(arr, len);
    for (int i = 0; i < len; i++)
    {
        cout << "Index=" << i << ",Id=" << arr[i].BookId << ",name=" << arr[i].BookName << ",title=" << arr[i].BookTitle << endl;
    }
    cout << "Finished in structArray7() and now is " << getTimeNow() << endl;     
    free(dtValue);
    free(uuidValue);
}

void getStructArray9(struct BookStruct2 *ptr, int len)
{
    for (int i = 0; i < len; i++)
    {
        ptr->BookId = (unsigned long long)i * i * i;
        ptr->BookName = (char *)malloc(40);
        strcpy(ptr->BookName,getUuidValue3()); 
        ptr->BookTitle = (char *)malloc(40);
        strcpy(ptr->BookTitle,getUuidValue3());
        ptr++;
    }
} 

char *getUuidValue3()
{
    uuid_t newUUID;
    uuid_generate(newUUID);
    uuid_unparse(newUUID, uuidValue);
    return uuidValue;
}
 

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

Pay attention to the char *BookName in struct BookStruct,when assign the retrieved uuid value to the struct char *BookName

At first,allocate memory to the char * BookName

ptr->BookName = (char *)malloc(40);

Then assign the retrieved uuid value dynamically by computer via strcpy method instead of = directly

strcpy(ptr->BookName,getUuidValue3()); 

Compile via 

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

Run ./h1