how to tokenize a string in c 2b 2b

1std::vector<std::string> split(const string& input, const string& regex) {
2    // passing -1 as the submatch index parameter performs splitting
3    std::regex re(regex);
4    std::sregex_token_iterator
5        first{input.begin(), input.end(), re, -1},
6        last;
7    return {first, last};
8}
9

1auto const str = "The quick brown fox"s;
2auto const re = std::regex{R"(\s+)"};
3auto const vec = std::vector<std::string>(
4    std::sregex_token_iterator{begin(str), end(str), re, -1},
5    std::sregex_token_iterator{}
6);
7

1//the program take input as string and delimiter is ','.
2//delimiter can  be changed in line 9;
3
4std::vector<std::string> tokenise(const std::string &str){
5    std::vector<std::string> tokens;
6    int first = 0;
7    //std::cout<<"aditya";
8    while(first<str.size()){
9        int second = str.find_first_of(',',first);
10        //first has index of start of token
11        //second has index of end of token + 1;
12        if(second==std::string::npos){
13            second = str.size();
14        }
15        std::string token = str.substr(first, second-first);
16        //axaxax,asas,csdcs,cscds
17        //0123456
18        tokens.push_back(token);
19        first = second + 1;
20    }
21    return tokens;
22}