Split string to float vector

#include <iostream>
#include <string>
#include <vector>

void split(std::vector<std::string> &ret, std::string source, std::string delimiter) {
    std::vector<std::string> tmp;
    size_t start = 0, end = 0;

    while((end = source.find(delimiter, start)) != std::string::npos) {
        tmp.push_back(source.substr(start, end - start));
        start = end + 1;
    }
    tmp.push_back(source.substr(start, source.length()));
    ret = tmp;
    return;
}

void split(std::vector<int> &ret, std::string source, std::string delimiter) {
    std::vector<int> tmp;
    size_t start = 0, end = 0;

    while((end = source.find(delimiter, start)) != std::string::npos) {
        tmp.push_back(std::stoi(source.substr(start, end - start)));
        start = end + 1;
    }
    tmp.push_back(std::stoi(source.substr(start, source.length())));
    ret = tmp;
    return;
}

void split(std::vector<float> &ret, std::string source, std::string delimiter) {
    std::vector<float> tmp;
    size_t start = 0, end = 0;

    while((end = source.find(delimiter, start)) != std::string::npos) {
        tmp.push_back(std::stof(source.substr(start, end - start)));
        start = end + 1;
    }
    tmp.push_back(std::stof(source.substr(start, source.length())));
    ret = tmp;
    return;
}

int main() {

    std::vector<float> d;
    split(d, "5.4 6.5 7.6", " ");

    for(int z=0; z!=d.size(); z++) {
        std::cout << d.at(z)*d.at(z) << std::endl;
    }


    return 0;
}