C - Convert time_t to string with format YYYY-MM-DD HH:MM:SS

Question

Hello, is there any way to convert a time_t to a string with the format YYYY-MM-DD HH:MM:SS automatically, keeping the code portable?

Answer 1

Your only real option off the top of my head is either to write your own routine, or use the ctime() function defined in POSIX.1/C90. ctime() is certainly worth looking into, but if your date is not in the right timezone already, you will run into issues.

EDIT: I didn't think about using localtime as mentioned by Jerry below. Converting it to a struct tm does give you more possibilities including what he mentions, and strptime().

Answer 2

Use localtime to convert the time_t to a struct tm. You can use strftime to print the desired data from that.

char buff[20];
time_t now = time(NULL);
strftime(buff, 20, "%Y-%m-%d %H:%M:%S", localtime(&now));