Generate random IMEI (15 digits) and ICCID (19 digits) with Lune checksum

genImeiIccid.cpp

#include <iostream>
#include <stdlib.h>

std::string generateIccid()
{
    char res[20];
    int sum = 0;
    int num = 0;

    for (size_t i = 0; i < sizeof res - 2; i++)
    {
        num = rand() % 10;
        res[i] = '0' + num;
        if (0 == (sizeof res - 1 - i) % 2)
        {
            num *= 2;
            if (num > 9)
                num -= 9;
        }
        sum += num;
    }
    sum = (10 - (sum % 10)) % 10;
    res[sizeof res - 2] = '0' + sum;
    res[sizeof res - 1] = '\0';

    return res;
}

std::string generateImei()
{
    char res[16];
    int sum = 0;
    int num = 0;

    for (size_t i = 0; i < sizeof res - 2; i++)
    {
        num = rand() % 10;
        res[i] = '0' + num;
        if (0 == (sizeof res - 1 - i) % 2)
        {
            num *= 2;
            if (num > 9)
                num -= 9;
        }
        sum += num;
    }
    sum = (10 - (sum % 10)) % 10;
    res[sizeof res - 2] = '0' + sum;
    res[sizeof res - 1] = '\0';

    return res;
}

int main()
{
	std::cout << generateImei() << std::endl;
	std::cout << generateIccid() << std::endl;
	return 0;
}