Using sscanf ( ), how to extract date from buffer that contain combined date and time  ?

Posted on 2014-02-11
Last Modified: 2014-02-12
iso8601_date_time_buf is pointer to const char.  It's length is Twenty bytes.  It contains combined date and time in format:   YYYY-MM-DDTHH:MM:SS
T is delimiter between date and time.  

int year;
int month;
int day;
sscanf (iso8601_date_time_buf, "%d-%d-%d", &year, &month, &day );

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A delimiter is followed by first two %d.  Do I need a delimiter after 3rd %d because day is in the middle of the buffer.
Question by:naseeam
  • 3
LVL 86

Accepted Solution

jkr earned 400 total points
ID: 39852157
Just follow the elimter scheme as in the string you want to parse, e.g.

int year;
int month;
int day;
int hours;
int minutes;
int seconds;
sscanf (iso8601_date_time_buf, "%d-%d-%dT%d:%d:%d", &year, &month, &day, &hours, &minutes, &seconds );

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LVL 86

Expert Comment

ID: 39852174
Just in cae I misunderstood your question: Using 'sscanf()', it's necessary to parse all the variable parts of your input string, otherwise you'll run into trouble.
LVL 86

Expert Comment

ID: 39852217
Or, a bit more general, independant from the parsing method you choose (and there are plenty): You have to parse all variable fields in order to achieve a correct result, since otherwise all methods are doomed to fail at these very fields by definition.
LVL 33

Assisted Solution

sarabande earned 100 total points
ID: 39853159
using c++ you would use stringstream like

char iso8601_date_time_buf[] = "2014-02-12 14:18:00";
std::istringstream iss(iso8601_date_time_buf);
int d, m, y, h, mi, s;
char c;
if (iss >> y >> c >> m >> c >> d >> c >> h >> c >> mi >> c >> s)

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you also could parse the date only and omit the time part or check each part separately:

if (iss>>y>>c)
     if (iss>>m>>c)
            if (iss>>d)

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that would allow to give a specific error in the else parts.


Author Closing Comment

ID: 39853250
Question answered.  sscanf ( ) explained very well.

Thanks for alternate solution, istringstream class.

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