C++ split string class in function not using strtok()

Question

I have a default constructor function that takes in a string class variable (not char*) and needs to tokenize that string by a delimiter which in my particular case is a comma. Since I am using the string class I cannot within my knowledge use strtok() because it expects a char* as an input and not a string class. Given the code below how can I split the string into smaller strings given that the first two tokens are a string, the third an in and the fourth a double?

private string a;
private string b;
private int x;
private double y;

StrSplit::StrSplit(string s){
  a = // tokenize the first delimiter and assign it to a
  b = // tokenize the second delimiter and assign it to b
  x = // tokenize the third delimiter and assign it to x
  y = // tokenize the fourth delimiter and assign it to y
}

Answer 1

Try bellow source-code : (test it online)

#include <vector>
#include <string>
#include <sstream>
#include <iostream>
#include <cstdlib>

std::string a;
std::string b;
int x;
double y;

std::vector<std::string> split(const std::string& s, char delimiter)
{
   std::vector<std::string> tokens;
   std::string token;
   std::istringstream tokenStream(s);
   while (std::getline(tokenStream, token, delimiter))
   {
      tokens.push_back(token);
   }
   return tokens;
}

int main()
{
    std::string str = "hello,how are you?,3,4";
    std::vector<std::string> vec;
    vec = split(str, ',');

    a = vec[0];
    b = vec[1];
    x = std::stoi(vec[2]);              // support in c++11
    x = atoi(vec[2].c_str());
    y = std::stod(vec[2].c_str());      // support in c++11
    y = atof(vec[2].c_str());

    std::cout << a << "," << b << "," << x << "," << y << std::endl;

}

The output will be :

hello,how are you?,3,3