str_to_map返回map<string，string>。如何让它返回map<string，int>？

#include <iostream>
#include <map>
#include <sstream>

std::map<std::string, int> str_to_map(const std::string& str) {
    std::map<std::string, int> result;
    std::istringstream iss(str);
    std::string token;

    while (std::getline(iss, token, ',')) {
        std::string key;
        int value;
        std::istringstream tokenStream(token);
        std::getline(tokenStream, key, ':');
        std::getline(tokenStream, token, ':');
        value = std::stoi(token);
        result[key] = value;
    }

    return result;
}

int main() {
    std::string str = "key1:1,key2:2,key3:3";
    std::map<std::string, int> resultMap = str_to_map(str);

    for (const auto& pair : resultMap) {
        std::cout << pair.first << ": " << pair.second << std::endl;
    }

    return 0;
}