Current date and time as string

I wrote a function to get a current date and time in format: DD-MM-YYYY HH:MM:SS. It works but let's say, its pretty ugly. How can I do exactly the same thing but simpler?

string currentDateToString()
{
    time_t now = time(0);
    tm *ltm = localtime(&now);

    string dateString = "", tmp = "";
    tmp = numToString(ltm->tm_mday);
    if (tmp.length() == 1)
        tmp.insert(0, "0");
    dateString += tmp;
    dateString += "-";
    tmp = numToString(1 + ltm->tm_mon);
    if (tmp.length() == 1)
        tmp.insert(0, "0");
    dateString += tmp;
    dateString += "-";
    tmp = numToString(1900 + ltm->tm_year);
    dateString += tmp;
    dateString += " ";
    tmp = numToString(ltm->tm_hour);
    if (tmp.length() == 1)
        tmp.insert(0, "0");
    dateString += tmp;
    dateString += ":";
    tmp = numToString(1 + ltm->tm_min);
    if (tmp.length() == 1)
        tmp.insert(0, "0");
    dateString += tmp;
    dateString += ":";
    tmp = numToString(1 + ltm->tm_sec);
    if (tmp.length() == 1)
        tmp.insert(0, "0");
    dateString += tmp;

    return dateString;
}

Since C++11 you could use std::put_time from iomanip header:

#include <iostream>
#include <iomanip>
#include <ctime>

int main()
{
    auto t = std::time(nullptr);
    auto tm = *std::localtime(&t);
    std::cout << std::put_time(&tm, "%d-%m-%Y %H-%M-%S") << std::endl;
}

std::put_time is a stream manipulator, therefore it could be used together with std::ostringstream in order to convert the date to a string:

#include <iostream>
#include <iomanip>
#include <ctime>
#include <sstream>

int main()
{
    auto t = std::time(nullptr);
    auto tm = *std::localtime(&t);

    std::ostringstream oss;
    oss << std::put_time(&tm, "%d-%m-%Y %H-%M-%S");
    auto str = oss.str();

    std::cout << str << std::endl;
}

Non C++11 solution: With the <ctime> header, you could use strftime. Make sure your buffer is large enough, you wouldn't want to overrun it and wreak havoc later.

#include <iostream>
#include <ctime>

int main ()
{
  time_t rawtime;
  struct tm * timeinfo;
  char buffer[80];

  time (&rawtime);
  timeinfo = localtime(&rawtime);

  strftime(buffer,sizeof(buffer),"%d-%m-%Y %H:%M:%S",timeinfo);
  std::string str(buffer);

  std::cout << str;

  return 0;
}

you can use asctime() function of time.h to get a string simply .

time_t _tm =time(NULL );

struct tm * curtime = localtime ( &_tm );
cout<<"The current date/time is:"<<asctime(curtime);

Sample output:

The current date/time is:Fri Oct 16 13:37:30 2015

Using C++ in MS Visual Studio 2015 (14), I use:

#include <chrono>

string NowToString()
{
  chrono::system_clock::time_point p = chrono::system_clock::now();
  time_t t = chrono::system_clock::to_time_t(p);
  char str[26];
  ctime_s(str, sizeof str, &t);
  return str;
}

#include <chrono>
#include <iostream>

int main()
{
    std::time_t ct = std::time(0);
    char* cc = ctime(&ct);

    std::cout << cc << std::endl;
    return 0;
}

With C++20, time point formatting (to string) is available in the (chrono) standard library. https://en.cppreference.com/w/cpp/chrono/system_clock/formatter

#include <chrono>
#include <format>
#include <iostream>

int main()
{
   const auto now = std::chrono::system_clock::now();
   std::cout << std::format("{:%d-%m-%Y %H:%M:%OS}", now) << '\n';
}

Output

13-12-2021 09:24:44

It works in Visual Studio 2019 (v16.11.5) with the latest C++ language version (/std:c++latest).

I wanted to use the C++11 answer, but I could not because GCC 4.9 does not support std::put_time.

https://stackoverflow.com/questions/14136833/stdput-time-implementation-status-in-gcc

I ended up using some C++11 to slightly improve the non-C++11 answer. For those that can't use GCC 5, but would still like some C++11 in their date/time format:

 std::array<char, 64> buffer;
 buffer.fill(0);
 time_t rawtime;
 time(&rawtime);
 const auto timeinfo = localtime(&rawtime);
 strftime(buffer.data(), sizeof(buffer), "%d-%m-%Y %H-%M-%S", timeinfo);
 std::string timeStr(buffer.data());