isNumber with overload

#include <iostream>

bool toNumberConv(std::string str, int &x)
{
    bool num = true;
    unsigned int i = 0;
    while(i < str.length() && num)
    {
        if (!isdigit(str[i]))
        {
            num = false;
        }
        i++;
    }
    if(num)
    {
        x = stoi (str);
    }
    else
    {
        x = 0;
    }
    return num;
}

bool toNumberConv(std::string str, double &x)
{
    int dots = 0;
    bool num = true;
    unsigned int i = 0;
    while(i < str.length() && num)
    {
        if ((str[i] == '.') && dots == 0)
        {
            dots = 1;
        }
        else if (!isdigit(str[i]))
        {
            num = false;
        }
        i++;
    }
    if(num && dots <= 1)
    {
        x = stod (str);
    }
    else
    {
        x = 0;
    }
    return num;
}

int main()
{
    std::string str;
    std::cin >> str;

    int toNumInt;
    double toNumDouble;

    bool isNumInt = toNumberConv(str, toNumInt);
    bool isNumDouble = toNumberConv(str, toNumDouble);

    if(isNumInt) std::cout << toNumInt << std::endl;
    else std::cout << "Ez nem egy int szam\n";

    if(isNumDouble) std::cout << toNumDouble << std::endl;
    else std::cout << "Ez nem egy double szam\n";

    return 0;
}