Unable to write on SD the same data showed on serial monitor

Hallo, I'm writing a code to log on a SD card the temperature and the humidity values at a given interval.
I can get the correct result in the serial monitor but I'm unable to get the same result on the SD.
The problem is only about the date and time which are setted by this:

       float h = dht.readHumidity();
       float t = dht.readTemperature();
       Serial.print("Hum: "); 
       Serial.print("Temp: "); 

which gave me this result in the Serial Monitor

2018-05-04 23:30:58 Hum: 58.10% Temp: 22.10
2018-05-04 23:31:04 Hum: 58.10% Temp: 22.10

How can I transform the date and the time in a loggable value? I'm really lost and I need some advice.

I'm using a ZS-042 Real time clock with these statements:

#include <DS3231_Simple.h>
DS3231_Simple Clock;

You can use the sprintf() function to format the output into char array and then write the char array to the SD card. Look it up, lots of references.

Is it DHT11 or DHT22 that you are using?

What is the name of the Library that you are using for DHT11/DHT22 sensor?

Do you know how to write to a file on SD card? If not, start with that. If yes, duplicate your code and instead of using Serial, use the file handle returned by SD.open().