#include <array>
#include <iostream>
#include <string>
 
std::string GetDateFormatString(const std::string& langCode)
{
    if (
       0 == langCode.compare(0, 2, "en")
       || 0 == langCode.compare(0, 2, "EN")
       )
    {
        return std::string("%1$i/%2$i/%3$i");
    }
    else if (
       0 == langCode.compare(0, 2, "fr")
       || 0 == langCode.compare(0, 2, "FR")
       )
    {
        return std::string("%2$i/%1$i/%3$i");
    }
    else if (
       0 == langCode.compare(0, 2, "ja")
       || 0 == langCode.compare(0, 2, "JA")
       || 0 == langCode.compare(0, 2, "jp")
       || 0 == langCode.compare(0, 2, "JP")
       )
    {
        return std::string("%3$i/%2$i/%1$i");
    }
    return std::string("%1$i/%2$i/%3$i");
}

#if defined(_WIN32)
#  define sprintfp _sprintf_p
#else
#  define sprintfp snprintf
#endif

std::string GetDateString(
    const std::string &langCode,
    int month, int day, int year)
{
    std::string fmt = GetDateFormatString(langCode);
    std::array<char, 32> buffer;
    buffer.fill(0);
    sprintfp(buffer.data(), 32, fmt.c_str(), month, day, year);
    std::string ret = buffer.data();
    return ret;
}

int main()
{
    std::cout << GetDateString("en", 11, 7, 2018) << "\n";
    return 0;
}