time_t troubles

[C+/-]

I have a string with the following contents: "1950-01-01 00:00:00".

I have the following code. It should create a time_t object from the string. But it crashes and I don't understand why..

tm dbTime;
dbTime.tm_year = atoi((s.substr(0, 4)).c_str()) - 1900;
dbTime.tm_mon = atoi((s.substr(5, 2)).c_str());
dbTime.tm_mday = atoi((s.substr(8, 2)).c_str());
dbTime.tm_hour = atoi((s.substr(11,2)).c_str());
dbTime.tm_min = atoi((s.substr(14, 2)).c_str());
dbTime.tm_sec = atoi((s.substr(7, 2)).c_str());
dbTime.tm_isdst = false;

// Seems to be correct:
cout << "datetime values read: " << endl;
cout << dbTime.tm_year << endl;
cout << dbTime.tm_mon << endl;
cout << dbTime.tm_mday << endl;
cout << dbTime.tm_hour << endl;
cout << dbTime.tm_min << endl;
cout << dbTime.tm_sec << endl;
cout << dbTime.tm_isdst << endl;


time_t t = mktime(&dbTime);  // returns  -1, error code
cout << ctime(&t) << endl;     // crashes

Why does mktime return -1? Is something wrong with the tm instance?

I wasn't sure where to post this. If it should be in the C subforum, please move it there.

Thanks

[matsp]

Perhaps because in most implementations, time_t starts from 1-Jan-1970. That's not guaranteed, but it's certainly quite common.

ctime shouldn't crash - that would probably be a consequence of the bad value tho'.

--
Mats

[C+/-]

Thanks, matsp!

I knew about the 1 jan 1970 thing, but somehow it didn't occur to me when debugging this problem.. Thanks for pointing that out.

[hk_mp5kpdw]

I have a string with the following contents: "1950-01-01 00:00:00".

dbTime.tm_sec = atoi((s.substr(7, 2)).c_str());

Typo? s.substr(7,2) is "-0". Is this actually s.substr(17,2) instead?